The Risks of Agriculture

The Risks of Agriculture -- and of Caterpillars in Close Quarters

Factory farming caterpillars.

Should I try to become the Smithfield Foods of the hickory horned devil production industry? I think not.

Most of the remaining hickory horned devils have pupated by now and most of the remaining lunas have made cocoons (again, email me if you would like any – otherwise, I’ll return them to the wild) but, frankly, I had a lot of late losses. This brings up a problem that is near and dear to my heart  (and related to the title of my blog)– the ecological problems that happen with agriculture.

What does "agriculture" have to do with raising caterpillars? Well, think about it – what is agriculture? It’s picking some species (or a set of species) that originally came from nature and creating special conditions that allow those species to prosper, unencumbered by the normal ecological balances that control population size and rapid growth – predators, disease, resource limitations, competition, bad weather, etc. Though it seems counter-intuitive to people who don’t know a lot about biology, these natural “checks and balances” are actually good for most species in the long-term, as they keep populations within “sustainable” (a word you’ve probably heard before) limits and, through natural selection, force the population to maximize the “fitness” (ability to survive) of its members, as well as maintain a healthy, diverse gene pool to address future needs. (A number of my previous posts have addressed these issues, as you may have noticed.) As the song says, “you’ve got to be cruel to be kind.”

With agriculture  – in other words, with human tampering to short-circuit this environmental system in order to increase an organism’s population for our own selfish purposes – predictably comes problems because the long-evolved  environment and ecosystem doesn’t  in fact just disappear when we start fooling with their parts. These predictable problems are really familiar to human civilization: exhaustion of soil nutrients (probably the biggest thing limiting agriculture and human population growth until the invention of artificial nitrogen fixation in the early 20^th Century), land degradation, weather-caused crop damage (especially from drought, especially before modern irrigation projects, though this is still a big,  unsolvable problem) and pests, predators, disease. These last three are really the ecosystem striking back, as the big monocultures that agriculture creates invite the complex biology of the environment to, as they say in business, “institute corrective measures.”

Pests (a term usually applied to insects) are mainly a problem with plant crops.  Big monocultures – vast fields of corn, wheat, cotton, soybeans – invite huge population explosions of the bugs that happen to be evolved to eat those specific plants. We mainly solve this problem through using huge quantities of arthropod-specific poisons we call pesticides, which, of course, cause other problems and are really only short-term solutions, because insects evolve and adapt quickly to poisons (see my earlier post on insect evolution and food plants) and eventually will become immune to anything that is not prohibitively toxic.

A big cornfield -- a monoculture of corn. The corn borer moth
thinks it has died and gone to heaven. It's just Iowa.

Predators (this is really a false distinction, since insect pests are really just predators of plants) are generally those parts of the ecosystem that attack livestock or animal agriculture – wolves eating sheep and cattle, hawks eating the chickens, etc. Since the predators of the few animals we grow commercially are not all that common in nature, we generally have “solved” this problem by eliminating livestock predators from the environment. This may seems like a good solution, but it too causes big problems. The population explosion of white tailed deer (and mice squirrels and other rodents that aren’t quite as noticeable)  and Canada Geese (now plaguing suburbs throughout the east), is a direct result of wolf elimination. And there are further downstream effects from that – you have perhaps heard of  Lyme Disease? It’s all only going to get worse.

And, finally, agricultural diseases – the problem topic I’m most interested in.  We don’t think much about the microbial ecology out there (the complex interactions is the biosphere of millions of species of bacteria, viruses and fungi) because we can’t see it . Our knowledge of these organisms is very new--we, in fact, really didn’t fully understand what the causes of disease were until the development of biology in the 20^th Century.  But  whether we know that microbes are playing a big part in the ecosystem or not, they still profoundly affect things. In plant agriculture, you simply can’t grow certain crops in parts of the country where certain diseases range. Wine grapes, for example, are basically impossible to grow in much of the American south where a certain leafhopper ranges, carrying with it a bacterial disease lethal to European grapes; the introduction of chestnut blight, a fungal pathogen, to North America basically eliminated the American chestnut, a once dominant tree in the eastern forests. If you are a wheat grower, just a single incidence of wheat rust is a major catastrophe, because it eliminates wheat as a crop, if it ever gets established.

This is all because monoculture itself is basically a complete denial of the realities of microbial ecology. In the environment, pathogens (microbes that kill or severely damage multicellular life) are relatively rare because (1) if a microbe evolves that destroys its host, it thus eliminates its food source (at least in the populations where it is present) and cause its own elimintatio; (2) pathogenic microbe populations are controlled by competition/predation by other more benign (and more successful) microbes in the microbial environment and (3) they are balanced by anti-microbial adaptations (like your immune system) that multi-cellular life forms have evolved over time. Generally, successful microbial species are those that have evolved to come to an ecological balance (think of it as a truce, or a trade agreement) with the hosts they live on/in and with the other microbes that also share that environment.

Monocultures mean growing organisms in unnatural crowds.
Pigs and chickens in factory farms.

Monoculture, which makes radical changes in the ecology, changes all that, eliminating many of the checks and balances and cooperative agreements that have been negotiated by the evolutionary process. This change thus allows microbes that otherwise not be well adapted to survive to actually flourish, and it gives a huge, easily accessible food supply for them to spread through with terrifying speed (hence the apt metaphor you sometimes hear of diseases spreading “like wildfire”).  “Easily accessible” is actually one of the largest ecological weaknesses in human agriculture: We grow vast fields of corn, house thousands of pigs in giant barns; in nature, populations are spread out across landscapes, mixed in with other competing species – if a new, deadly pathogen emerges, it may kill off a local population but then die off and subside before it’s presence in the environment becomes massive and it is a threat to the existence of the entire species. In other words, there are natural barriers to the uncontrolled spread of most pathogens.  By re-arranging things to suit our needs and wishes, we have unwittingly eliminated most of those barriers.

 The struggle with disease and microbial ecology is really the biggest problem in animal agriculture, and, frankly, it’s not a winnable battle.  We are currently using some very serious (and seriously dangerous) tools to combat this problem. Read up on the widespread use of antibiotics in livestock farming and Google “antibiotic resistance” if you want to begin understanding the catastrophe this is leading to. We simply can’t eliminate the unnatural spread of pathogens in monocultures of animals without causing still larger problems.

Make no mistake about it, growing caterpillars in sleeves is exactly the kind of unsustainable monoculture practice I have been describing, and, like any unwitting farmer, I’ve been plagued by totally predictable problems. As I’ve described in earlier posts, my unnaturally large populations and limited natural supply of nutrients (in my case, the sweet gum tree leaves that I can reach without a 12-foot step ladder) has led to problems – stunted growth and the lunas chewing through their sleeves, allowing parasites to attack. Then, further, the weakened populations of caterpillars became more susceptible to bacterial diseases, which, because of unnatural crowding, spread rapidly through my stock. The end result is that I only have about a dozen live pupae of each moth, after starting with over 200 eggs. You may remember me talking here in an early post about the natural adaptation of giant silk moths to spread their egg laying over a large geographic area and many trees. The catastrophic spread of disease under crowded conditions is yet another reason why that is necessary for the species.

Of course, my agriculture here has been small scale, and I have still had a modest success – I’ve successfully taken more caterpillars through the larval stage than  would have likely survived in nature.  Think of me being like a small, subsistence farmer, who has many farming disasters but still manages to grow more food crops than he could ordinarily forage from nature.  It’s still a disaster, but the practice is less unsustainable than what happens when you try to ramp it up to a larger scale. If there really was a big market for hickory horned devils, it might lead someone like me to think about developing a factory farm for moths… At which point, a wise person might consider pursuing another profession.

Why Are Insects Deceptive?

Why Are Insects Deceptive?

In my last post, I talked about mimicry in hickory horned devil caterpillars and I’ve talked about it before.  It’s an interesting issue in looking at insect ecology, behavior and evolution. When you start looking for it, you see it everywhere.

Why are luna caterpillars bright green and ribbed? They are mimicking the green, ribbed surface of the leaves they live among, since the leaves are everywhere and don’t attract attention. Birds and other predators don’t eat leaves.

It’s essentially camouflage, and it can be remarkably specific. Remember an earlier discussion I posted in which I talked about how regal moths and their relatives were tropical invaders who breed only in the late summer rainy season? Well, if you think about it, this explains some of the unusual coloration of some of these moths – coloration which,  when they come to the light on your front porch, certainly seems to stand out.

Take for example, one of the regal moth’s cousins, the large, bright yellow, imperial moth:

This moth, seen by itself, certainly seems to be showing off rather than hiding… but that’s only because we’re seeing it out of context from the woods in which it lives, during August, the season when it is flying. At that time in the late summer in the south, a number of trees prematurely begin to shed leaves. A common forest tree that does this is the tulip tree. Here is a picture of a tulip tree, taken in the season when these moths are flying:

… and here is a picture of a fallen tulip tree leaf. Notice the resemblance to the color pattern of the imperial moth?

Here are some other members of the subfamily Ceratocampinae, all also late summer flying, all also dead leaf mimics:

 Why do they mimic dead leaves instead of the more common green leaves? Remember that dead leaves fall and flit around on the breeze and moths fly. It’s a better match.

Remember my post about the second instar caterpillars (and many others) looking like bird poop? That too is taking advantage of a common piece of the specific environment the caterpillar lives in and using camouflage to blend in with it. Similarly, a lot of caterpillars are also twig mimics:

Why are bugs so deceptive? I’ll talk about this more in a later post, but the short answer is first that, among animals,  arthropods are small (their size is limited by the way they absorb oxygen into their bodies) and thus tend to be prey to larger animals (birds, lizards, amphibians, etc.), which means that predator avoidance is a big survival issue.  Secondly (and more importantly, really) because they are biologically equipped to take great advantage of the adaptive capabilities of evolution – they produce large numbers of offspring which get heavily “selected” by the struggle for survival – 500 hundred eggs may result in two surviving, breeding adults (if they are lucky); they also breed frequently, producing from one to several generations every year. In short, their genes have a lot of opportunities to try experimental combinations, and, when they hit on some new design that shows some promise, they get to make a lot of drafts to get it right.  When you live like this, you can develop some amazing adaptations to fit your environment. 


Bibliography

Wagner, David L. 2005. Caterpillars of Eastern North America. Princeton University Press, Princeton.

Midlife Crisis

4th instar hickory horned devil doing the limbo. Must have been the tequila.

Midlife can be… ugly.

I changed the sleeves today -- I ignored my own wisdom and made the sleeves smaller than the ones I made as a teenager, which means I have to transfer caterpillars to new branches when the leaves all get eaten. With small caterpillars, this isn’t easy, so it’s not what I recommend other people do. Use an old double bed sheet, sewed in a tube.

Still, there are advantages to moving the caterpillars – you get to see how they are all doing.  Interestingly, I’ve lost about 2/3 of my hickory horned devils, primarily, I think to disease or natural mortality when they were in the 1^st instar (when they were really little). I have about 40 left, which is fine – 100 6-inch caterpillars would be pretty hard to maintain. This kind of drop-off between hatchlings and larger caterpillars is not unusual – I assume that it’s one of the reasons why the moths lay so many eggs. But the survivors seem very healthy, with “only the strong” surviving.  In contrast, the lunas have had very little drop-off in population – they are all smaller (still 2^nd instar) but I have at least 100.

A variety of instars hanging out together.

What I find most interesting though is a big variation in the rate of growth among the hickory horned devils – in the sleeves there are a lot of 3^rd instars (about an inch long) quite a few 4^th instars ( 2 -2.5 inches – they will grow to about 4 inches before their final molt), and a few that are still 2^nd instar (less than an inch). All these caterpillars hatched within five day period, so that’s quite a spread. Why some are growing much faster than others, I can’t guess. It could be genetic differences: as I said in an earlier post, caterpillar broods can have a lot of variation in appearance, for example. It could also be accident (some caterpillars found more nutritious leaves than others) or disease/injury – some got a little bit sick and it slowed their growth. Or it could be something totally different.

A shed skin. /This is something human kids don't have to do when they move to the next grade.

My guess is that this is genetic variation. The probable reason why there is so much variation in the appearance of brother/sister caterpillars within single broods (if you look at the previous post you will see photos of two Pandora Sphinx caterpillars – one green, one orange – I have seen four different color patterns within a single brood) is that trying out different looks is like giving nature a choice. Who knows which one may carry a hidden advantage in any given time and place? Similarly, caterpillars who grow rapidly may have a survival advantage over slower growing ones… or vice-versa.

…Which brings up the issue of the current appearances of the 3^rd and 4^th instar caterpillars. What’s up with that? As I blogged about a couple of posts ago, the mottled appearance of the 2^nd instar caterpillars mimics bird droppings, giving those caterpillars a good disguise from hungry birds. But the 3^rd and 4^th instars are solid chocolate brown, with relatively large (almost leglike) horns. While the brown color could match the bark color of a twig, these guys seem to spend all day chewing on the green leaves, where they stand out. The hors make them stand out more, but aren’t large enough to seem credibly threatening. I’m puzzled by how this works for the bugs at this stage in their lives – if you have any ideas, let me know. In any case, they’re beginning to look really cool, in an “Alien vs. Predator” kind of way, which is good enough for me.

A Southern Strategy

The votes are in…

… and surprise, surprise, the southerners have simple tastes.

As I noted a couple of posts ago, I decided to try a simple experiment with the hickory horned devils (aka regal moth caterpillars) and how they react to different foodplants. I did this because they are known to eat a wide variety of trees, but some of my source books  say (this is what scientists call “reviewing the literature”) that ” local populations may have different preferences.” I decided to try my caterpillars on sweet gum and hickory, both of which are described in the books as “primary” choices for the moth.  I assumed that they would be willing to eat either, but I was going to test which produced bigger, healthier caterpillars.

Well, as I said, surprise, surprise – the experiment was over almost before it began. When I gave some of the caterpillars pignut hickory (the most common hickory in our area), they clearly refused to eat it. Newly hatched caterpillars sat together on the glass walls of their hatching cage, like kids huddling in a crowd outside a classroom they don’t want to enter, and wouldn’t go near the leaves, though they were fresh and clean. After a day and a half, I began to worry that they were going to die if they didn’t eat, so I also put in some sweet gum leaves, which their earlier hatchlings had already accepted readily. Within an hour, they were on those and eating – you can see this in the picture below.

 1st instar caterpillars on sweet gum leaves. Untouched hickory leaves are in upper left corner.

So, these Charlotte-area hickory horned devils  have a definite preference for sweet gum – I would actually call it a requirement, since I’m pretty sure they would have died before eating the other plant. If I had more caterpillars to and if I was willing to let them die, I would have tried a lot of other plants and I would have pushed the experiment to the bitter end. This might have given me what scientists call “solid experimental confirmation” of the conclusion that my caterpillars exclusively feed on one tree. Actually, a fuller experiment would have been to run the experiment with caterpillars from multiple local moths (to make sure this moth’s caterpillars were not just freakishly picky) and at the same time also running the experiment with caterpillars from a moths caught in other places, say somewhere in the deep south and somewhere in the upper midwest. That would take some work, so forget it for now.

Nonetheless, I have a solid “hunch” that this piece of information is “meaningful.” Here’s why: the food preferences of my caterpillars is clear, it agrees with other “field sightings” I’ve had (the only fully grown hickory horned devil I’ve ever seen here was feeding on a sweet gum tree).  I know from long experience that clear insect behaviors are rarely “anomalies” (something unique).  Insect populations are large in any given area, population interbreeding happens every year (many times a year in some species) and natural selection weeds out “bad” behaviors with a fine-toothed comb. In other words, in the normal word of insect evolution, the major details regarding bugs in a local environment tend to average out to what works best. If my bugs like sweet gum over all other foods, chance are the whole extended family (the whole Charlotte-area hhdevil tribe) feels exactly the same way, just like I can bet you most of my red-state neighbors won’t be voting for any atheist-socialist-gun-control candidates this year (I could be wrong). The regional cuisine of Citheronia regalis  appears to be limited to sweet gum (ideally, deep-fried).

Though the best source books I have don’t say anything about this, a quick web-search of some insect/nature sites, does have some people commenting that southern populations of the moth prefer sweet  gum.  Most of these reference are vague/uncertain, clearly because no one has really studied the matter. The truth is, research in insects in general (except crop pests), not to mention research in something specific like the larval behavior of a single moth,  is not done much or well-funded, so no one really knows what’s going on here. In this age where we know a lot about a lot of biological fine points like individual genes and proteins, it sounds strange to say, but common features of nature around us have not been well-studied – by professionals. So the science of this really depends a lot on the “field reports” of amateurs like me. Think of it as mobilizing a lot of unpaid interns to do data collection.

So, I say, let’s not let our lack of scientific validity stop us from going forward with speculation here:  back to the “tentative data” I have regarding the food choices of a mid-southern population of the regal moth…

Consider the history…

 If southern regal moth populations are much more specifically focused on eating sweet gum, how does this make sense, when other populations (northern populations) are known to eat a lot of other things – and these other foods are all around in the south?

Let’s look at it the other way – do northern populations eat other things because of what is available in the north? Let’s look at range maps for both the regal moth and for the sweet gum tree:

 Though the ranges look pretty much alike (sweet gums can’t take the long, cold winter of the north and regal moths, which pupate in the ground, without insulating cocoons, probably also have an issue with cold), I notice that the range of the regal moth is somewhat larger, going a little further north than the sweet gum tree. So … northern populations of regal moth in, say, New York or Massachusetts,  must eat something besides sweet gum. This may be why the books describe the other plants as known food for the moth. If the moth’s range started in the south, eating sweet gum there, and expanded north, then it had to evolve to eat other foods in order to move further north…

We actually know that the moth started in the south and expanded northwards (as I explained in an earlier post) because we have a geological record of relatively recent (only 13,000 years ago) ice ages when glaciers covered North America about as far south as I live now. When the ice receded, plants and animals (including the regal moth and the sweet gum) moved back in to recolonize the land, scrubbed clean by ice. apparently, the sweet gum has not been as rapid in its northern expansion as the regal moth. Trees can’t fly, so perhaps the range difference is simply the result of difference of the two species spreading at different speeds across the landscape, but the maps suggest different ideas. Notice that the sweet gum isn’t present in higher elevations in the Appalachian Mountains  but the Regal Moth is – this tells us that the sweet gum is probably more sensitive to cold than the moth.

So what happened when the ice receded? It didn’t all happen at once, but when it did, large areas of land were first colonized by more cold tolerant species like hickories and walnuts, sycamores and ashes --  the sweet gums could only arrive when the south became pretty warm. The regal moth, if it had an ancestor living in the deep south (or if it was an invader from Central America, as I speculated before), had to be/become a “generalist” with very flexible food habits if it wanted to take advantage of the new landscape, so it learned to tolerate a wide variety of foods…

But the moth wasn’t always a generalist. Back before the ice, when there was no new, unsettled landscape suddenly open, the moth’s ancestors surely had done what most other moths and butterflies do – evolved a special interdependence with a specific plant or family of plants (see earlier post for explanation of how this works), because that strategy seems to work well. What was the foodplant that the ancestor ate? My “hunch” (based on extremely sketchy evidence) is that it was the sweet gum or its ancestor. One thing we tend to forget about evolution is that, though new gene combinations result in new features, the genes that made the organism what it was before are generally not lost, at least not for a while.  this means that most of  the genes that helped the regal moth ancestor live successfully with a specific host plant are still back there in the genome, and, once the conditions  return that made them useful  in the past, natural selection will encourage those genes and the traits they cause to return. The sweet gum is back… and the regal moth is reverting to its ancient ways, its ancient strategies of survival, its ancient tastes.  I certainly can’t prove it, but that’s my best guess.  Again, it’s fun to start with a little hard information and… speculate.

“Oh, I wish I was in the land of cotton, old times there are not forgotten…”  Now there’s an idea the bugs share.

Bibliography:

Tuskes, Paul M., Tuttle, James P. and Collins, Michael M. 1996. The Wild Silk Moths of North America. Cornell University Press, Ithaca, NY.

Petrides, George A., 1988. A Field Guide to Eastern Trees.Houghton Mifflin Company. Boston.

Imagining the Moth

The female regal moth I caught on July 26 was dead by last night, having laid 135 eggs (which entomologists call “ova” – scientists like to have their own jargon) . I’ve cut them out of the cardboard container I kept her in and put them in the clean glass container you see above for careful monitoring. The standard egg laying container is a paper grocery bag, but I didn’t have one, so I made due with  a stationary box, which did the job. They are the largest lepidoptera (butterfly/moth) eggs I’ve ever seen and they are a beautiful translucent green, except for a few, which are now partially brown. Those are that way because the eggs are transparent and you can actually see the embryonic caterpillars developing inside – the brown is their heads—I’m guessing some will hatch tomorrow. I have saplings of their foodplants ready in pots – when they are really little I want to grow them inside the house where I can control the environment.

Before you feel too sad for the moth who died for this , I need to say don’t fret – she accomplished her primary mission in life: laying eggs. Giant silk moths only survive a few days as adults in the wild, living entirely off fats that they accumulated as caterpillars. They have no functioning mouthparts and they don’t eat.  They have only two missions – to mate, and to lay as many eggs as possible.

I”ll talk about their mating behavior another time (because it’s an important topic), but their egg laying is also interesting. Regal moths, like many of their close kin, often fly great distances, depositing an egg or two on one tree, then flying a quarter mile to lay another egg. There are a lot of possible explanations for how this behavior evolved.(I like to call these “explanations” “hypotheses” because no one actually knows how the pressures of nature encouraged the behavior’s development, and, frankly, it’s hard to imagine an experiment that would prove the “real” cause. Honestly, what follows is all unproven speculation – intelligent guesses. In science, the next job would be to find some clever way to test these ideas – to design an experiment and then collect solid information – “data..” However, nature – the world outside is a messy, complicated place and coming up with intelligent designs for such experiments is very, very difficult. For now, I’ll stick to the fun, imaginative part – the hypotheses.

 My personal best guess  for why regal moths have evolved to fly long distances and lay single eggs is that, since these eggs grow into very big caterpillars, it would be a bad idea for too many of them to be on one tree because they are likely to attract the attention of predators (such as birds) and once a predator has found one caterpillar, it is going to be primed to see another one nearby. So, this hypothesis says I saved the female moth the effort of flying all over the forest to lay her eggs, so she probably was able to get more laid before her fat-stored energy ran out (fat is really just a chemical battery, if you think about it). She had to lay them all together, which might be disastrous in nature where there are birds, but I’ve got her back – I’ll protect her caterpillars from predators. This makes me the good guy. Really.

However there is another “hypothesis” for why this moth has evolved single egg rather than mass laying behavior and this explanation perhaps means that I’m not being so clever in “farming” these caterpillars. Some of the regal moth’s near relatives, the oakworm moths (species in the genus Anisota), do tend to lay their eggs in big masses, and the caterpillars feed together in big troops, especially when they are young. (Herding together must serve some kind of protective function for these caterpillars, like it does for bison and schooling fish and ducks and starlings and the like, but I have no idea how that works – make your own hypothesis.) Oak moth caterpillars are considerably smaller than regal moth caterpillars at maturity and they grow up faster. Importantly, this means they have less time chance to catch a disease that could spread from caterpillar to caterpillar quickly, wiping out all a moth’s brood in one rapid epidemic.

       Young oakworm moth (A. osalari) caterpillars. National Park Service photo by Sally King.

This is a familiar problem to anyone who has ever tried to raise a lot of giant silk moth caterpillars  – you have to grow them in crowded conditions (you’re really “farming” them) and various diseases can appear and destroy your project. So perhaps another explanation (hypothesis) for why the regal moth lays single eggs is that this protects long-maturing caterpillars from spreading the diseases a few are likely to catch during a long period of infancy. This could be the explanation, or both explanations could be right or… something else entirely might be the cause. Nature is complicated and it’s hard to imagine all the problems that might come up in the life of a moth.

But it’s still fun to make guesses about the evolution of unusual characteristics in a species. One other feature of regal moth egg laying behavior that I also think is a bit strange is the fact that these moths produce only one generation a year, even here in the south where summers are long. This is actually not typical of most giant silk moths. Lunas, for example, have at least two generations a summer here in North Carolina, and researchers have noticed that they have three in Texas. The first lunas hatch and lay eggs in April here, but the regal moth waits until the end of July or August to hatch, mate and start laying eggs. Why?

We can reject the explanation that the moth has only enough time for one generation a year because it is so big that it takes a long time to grow. It does take a relatively long time to grow, but not really that much longer than a luna, which goes through the whole cycle twice. So let’s add another piece of evidence: its closest relatives (other species in the sub-family Ceratocampinae) also have only one generation (one “brood” as scientists say, or “univoltine” behavior) though many are much smaller moths. The authors of The Wild Silk Moths of North America  have suggested what I think is a convincing hypothesis for this: “In the United States and Canada the greatest number of species occur in the Southeast. Midsummer flight in warm, humid weather maybe an adaptation related to the tropical affinities of the group.” In other words, the authors note that relatives of these insects are a lot more common in the American tropics, so species like the regal moth may represent relatively recent invaders from tropical climates and they may still have hold-over physical adaptations from their not-too distant past, such as favoring the time of the year when North Carolina feels like Mexico or Honduras. In the tropics, the moths lay eggs in the rainy season, since that’s when the food plants are freshest. Perhaps these tropical moths have carried the home country behaviors here.

 This is another perhaps un-provable hypothesis regarding evolution, but I like it because it again makes you expand your imagination to consider yet another dimension that can affect things: history. Consider the fact that only a little over ten thousand years ago (a blink of an eye in biological history, really) most of North America was covered by the expansion of a thick ice sheet. (Ice might have been a mile thick where I live now.) When that happened, where did all trees, bugs and other animals go? They either died out or they moved south to where there was no ice (Florida would have been ice free, but much cooler than now.) Then, when the ice receded back to the north, old species returned and some new species invaded from the south. The regal moth and its relatives may have been just such invaders – they still carry the signs of their history in the way they live.

So, in order to come to grips with how a moth works you need to imagine all kinds of things – what it’s really like out there – and what it must have been like out there a long time ago. Who knows what the most important “causes” were? There were certainly many, all working together and the result of the biological evolution they caused is the moth we have now. To really know we await clever minds, brilliant experiments and … data.

Moths, Memory, and Motivation

It’s this moth’s fault. I’m blogging.  About bugs.

Also about biology.  About science and what it can tell us about our lives and our world.  And, I guess, I’m blogging about me and about why I think this stuff is cool.

To be honest, I have been looking for an excuse to start a blog for quite some time. I write about science for a living. I also work with university scientists and spend a lot of time convincing them  to share what they know with the public – particularly through blogging and other social media. It’s a little bit phony for me to lecture others about this when I don’t do it myself.

The problem I have in doing a blog is that most of the things I know a lot about (and want to write posts on) are subjects that very few other people would want to read about. I set up this blog a couple of years ago to write about epizootic diseases – epidemics that affect wild plants and animals and that are, in some ways as big a threat to the stability of the natural world around us as climate change and human development. It’s an important topic, but the problem is that it’s also astoundingly complicated and something very few people outside of some  landscape ecologists care about. More people should care, but, well, they just don’t. What’s the point in writing something that no one else out there is going to want to read?

In a big way, the problem is public education in science. Science, as most of us know it, seems to be dry, difficult and (I’ll say it) boring. However, it has never seemed boring to me, even though I am not a scientist myself.  I wish I could say this is because I was lucky enough to have had a great science education when I was younger, but, honestly, I didn’t. Though my primary and secondary education wasn’t bad for the time (in the 1960’s and early 70’s), I had virtually no science classes until high school, and science classes there were very weak. I went to an Ivy League school for college, and there science was extremely demanding and technical and… pretty unimaginative. I took the classes I had to and then majored in English. I became a writer. Science, I decided, was disappointing.

Yet I kept a wistful eye on science, waiting to see something that would change my mind.  (Eventually it did, but more on that some other time. )

My science education – a personal history

Despite my education, I have been naturally drawn to science.  I grew up with the practice of scientific thinking, though I certainly didn’t know it at the time.  I lived in a beautiful place during my childhood – Ithaca, NY – in a landscape full of well-kept woods and beautiful streams, with impressive waterfalls, gorges and a big lake, and my friends and I spent most of our childhood rambling through it all,  hiking, swimming and fishing… and marveling at the oddities and complexities of the nature around us. We saw things when we played: crayfish, waterbugs, salamanders, wasps, bees, spiders, frogs, toads, fossils, trees, wildflowers, wild berries, hawks, song birds,  snakes, lizards, mushrooms, caterpillars, butterflies… and we were curious about them all. We collected anything that crawled, flew and swam (looking back on it, our mothers were saints) and wanted to know more about them, to understand them because they were alive and strange. We asked our parents for information.They. knew a bit, but not much. We read books, which told us more – the Golden Nature Guides, the Peterson Field Guides – but still not enough. In the end, we taught ourselves.

Like all scientists, we began to specialize. Because our parents had bought us butterfly nets (catching butterflies was an acceptable childhood “hobby” in the 1960’s, like stamp collecting), we started making our own butterfly collections.  We loved this hobby because it was easy and fun to go on “missions” to collecting spots, and because it was both physically and technically challenging (the really cool butterflies were both hard to find and hard to catch – you had to know where to look and you had to be fast).  There was biology to learn – butterflies were tied to their foodplants: black swallowtails hung out near queen anne’s lace, monarchs near milkweed; these flowers grew in different places. There were technical skills to learn – how to catch butterflies without damaging them, how to kill them quickly and effectively, how to mount them and dry them (we found biology supply catalogues, we bought spreading boards and insect pins),  how to preserve the important data concerning where and when we caught them.  It was complicated and seemed grown-up. We became “experts” in something, which was cool. Our parents were (I guess) amused and…  a little impressed.

We quickly found out that something that seemed simple – catching a bunch of pretty colored insects and putting them in boxes – was actually demanding and nearly endlessly complex and mysterious.  A lot of the butterflies that were the coolest, the rarest, the most beautiful, lived in strange places – treetops, the edges of swamps and streams, sunlit clearings in deep woods – and only flew in certain seasons and specific times of the day – early spring, late afternoon.  We learned why – mating rituals, foodplant availability, lifecycle requirements. We didn’t just read, we observed. We learned that the books were not always right – insects are really variable and behave differently in different locales.  We developed hypotheses, collected information that supported or contradicted them. We learned, at least concerning a couple dozen species of butterflies in the part of upstate New York where we lived, how nature worked. Nature taught us the science we needed to use, and science taught us what there was to know. (Not that we knew enough to call it “science, “ of course.) It was like the world had opened up.

And the world kept opening wider: butterflies are a fairly limited group of insects, but their cousins, the moths, are much, much more numerous and diverse.  Some of them – the giant silk moths, the sphinx moths – are even bigger and more spectacular than the biggest butterflies,  yet few people notice them. Moths fly at night and hide during the day, so they live in an unseen world. One of my friends took a vacation at a cabin at one of the local state parks and came back with giant purple-eyed polyphemus moths and ethereal green luna moths that he had caught at the cabin light… we had read about them in books, but they seemed mythological and perhaps part of a forgotten past. Who knew that they had been around us all along?  There was a whole new world out there that we knew nothing about…

And so, as we approached adolescence, we began taking journeys into the countryside where lights were scarce (and woods and fields were broad) and staying out very late on summer nights, having found our own lost world.  There were hundreds and hundreds of species, some drab, some strange and exotic, almost all of them totally new to us, though we thought we knew nature so well. We learned light collecting techniques, baiting techniques to attract different species. We learned a lot more about caterpillars and their biology than we ever had before.  The caterpillars had always been there too, all around us in the trees and plants and bushes, but ingeniously hidden.   We learned how to find them, and marveled at their weird shapes and colors. We learned how to get moths to lay eggs, and how to raise the young. We learned about the predators and parasites that keep the moth populations from exploding (and that really upset a boy trying to raise a cool caterpillar). We began to learn ecology. Again, there was layer after layer of mystery in the world, hidden, but waiting to be explored.

I think the memory of my natural “awakening,” and the wonder of it all has been a driving force in my life. I began to understand that the world around me, despite technology, our comfortable homes, our cars and planes, is still deeply mysterious, and even the smallest things around us hold great mysteries that are still waiting to be explored, to be experienced and grappled with, to be finally (or at least somewhat) understood.  I guess my adventures with nature made me feel  curious and that curiosity has driven me ever since, whether I was collecting butterflies, or reading great works of literature, or studying the intricacies of human behavior.  As a science writer, it gives me an almost immediate sense of fascination concerning every subject I write about, whether it’s quantum physics, biochemistry, genomics, plate tectonics or patch dynamics, bioinformatics or demographics. There are things there that are unknown but that can be discovered and known. These things are amazing, if you give them your mind.

This is how I am and how most of the people I work with are, but how to get others to share this experience – to understand that science is really the great adventure of our time… well, that’s the problem.

Hence, this blog…

And so,  I looked out the window the other day and saw this moth … and had an idea.

It was not just any moth – it was an extravagant, large, orange and yellow moth – Citheronia regalis, aka the regal moth (for a better photo on the web, see: http://entnemdept.ufl.edu/creatures/bfly/regal_moth01.htm ) and, despite my aforementioned experience in collecting, it was the first time I had ever seen one alive in the wild.  In the world of American moths, it’s a famous moth. I make no exaggeration when I say that as a child I probably would have been willing give you one of my finger in order to get one. It’s not terribly uncommon here in the south (it's not common either – no giant silk moths are), but where I grew up was on the edge of its range, and the only examples I knew of from my town were in a university collection. 

The moth is one of the most beautiful insects in North America, but what the insect is really famous for is its huge, bizarre caterpillar. The caterpillar has its own name – it is popularly known as the “Hickory Horned Devil” -- and I think I can safely claim that it is one of the most unusual-looking insects (beautiful or terrifying or disgusting, depending on your perspective -- see this web video: http://www.youtube.com/watch?v=61thTKLcYhE) anywhere. From my own, admittedly child-like, perspective, it’s just plain cool.

Though I was looking out a window, about a dozen feet away,  I could tell immediately that it was a female (some training never leaves you). I also immediately knew that she had to have in her at least 100 fertilized eggs. I have learned that a newly hatched female giant silk moth will not fly anywhere until she has been successfully fertilized by a male (more about this in a later post). I was not tempted to collect her --her wingtips were damaged (this probably happened when she emerged from her pupa), but her color looked very fresh otherwise, which meant that she still had most of her eggs… I’ve never raised one of these particular bugs, but I know pretty exactly how to do it from rearing other giant silk moths, and I have some good source guides to help me (see brief bibliography at the end of this post).

 I have the technology… So I entertained the idea that I might try rearing the eggs (she’s now laid most of them) from egg to pupa, blogging as I go. Then, yesterday I found another female giant silk moth (a female luna moth, pictured above) while out walking my dog. The universe was clearly telling me to do this project.

Raising large caterpillars is an “interesting” experience where there are regular visuals to share (caterpillars change a lot as they grow), useful instructions to be passed along (for anyone who is interested in doing this too – believe it or not, you can actually sell live pupae to collectors on the internet) and a fair amount of science can come into play. I’m even going to try a simple experiment: as  I mentioned before, while C. regalis has been well-studied, there are still issues involving the biology of local vs. species-wide biology that are poorly understood.

For me, this is the point – I want to try doing and writing about “citizen” or “backyard” science that is accessible to broad audiences (I’m as interested in talking to younger people as I am to adults), on a topic that might-perhaps-maybe be appealing to the kid in all of us. (Or, if you hate gross bugs, you might read for the horror factor.)

And, yes, it’s a project, kids, that you can try doing at home. If I am successful at raising a number of regal moths/lunas to pupa/cocoon, I’d be willing to share them with some of you (for free), so you can try breeding and raising yourself. My only caveat to that offer is that I won’t send these outside the continental United States (where, at least theoretically, these moths can naturally range and not be invasive species). I will send out  at least two of one species per request, first-come-first served. If you’re an adult making the request, that’s fine, but I’d prefer that these be used for some educational purpose, rather than hatching them for perfect specimens for a collection.  Anyway, I’ll post more about that later when I’m closer to having some successfully reared insects.

My regal moth eggs were first laid July 27, 2012 and the luna laid her first egg last night (7/29) and they  are expected to hatch 6-10 days from laying. My next post will be when they do.

Bibliography:

For an excellent book about giant silk moths and their biology, see:
Tuskes, Paul M., Tuttle, James P. and Collins, Michael M. 1996. The Wild Silk Moths of North America. Cornell University Press, Ithaca,NY.