JD

I captured a couple woolybears in Northern California to bring down to Los Angeles for my daughter to raise. I wasn’t sure if they would survive since the climate is obviously much warmer down here. I placed them in a container with dandelion in the garage and one died and the other built a cocoon. I discovered the female one day had emerged and was depositing eggs in clutches on the back of the enclosure.

After she had layed 30-60 eggs I released her although she had no interest in flight.

I had read that the moths fly off to breed, so then how is it this moth emerged with eggs without any contact with a male moth (presumably)?

Not a lot of information is available about the eggs and gestation periods, early food and care etc. The eggs were often found split open like a stepped on ping pong ball but the enclosure screen was too large to keep them from escaping.

My question is do the months have the ability to breed Asexually?

Did the caterpillar that died trigger it or could it possibly have mated as a pupae?

One last thought is, have any other species of moths been known to interbreed?

Could be a long shot but a Hyles Lineata was spotted flying around my garage that served as my reminder to check on the Isabella Tiger Moth.

Sounded like you guys have had a successful breeding program and might shed some light or do you just collect them in the wild?

Thank everyone for their input on solving this mystery.

CR

Thanks for your interest in thinking critically about our research on self-medicating caterpillars. A bit of natural history on these caterpillars and their foraging habits will help you understand why we believe our results suggest that these caterpillars really do practice self-medication in the wild. They are unusually mobile for lepidopteran larvae, moving across the ground at a clip of 10 cm per second or faster. They sample small herbaceous plants quite frequently, and graze among them at a rate of 1-2 plant species per hour. This mobility is not likely to be very costly at all because the energetic demands are relatively small compared to flying insects or warm-blooded species which have thermoregulation on top of energetic costs for movement. Moreover, the caterpillar’s diet is rich in carbohydrates from plant tissue, giving them plenty of energy. My colleagues and I have done extensive observations of the caterpillar’s foraging behavior in the wild (Arizona) and in the lab. Based on a series of previous publications (cited in the PLoS paper), we know that the caterpillars feed selectively, and frequently feed on plants containing the alkaloids even when they have not been parasitized. However, the finding in our recent PLoS paper shows evidence that they increase their ingestion of alkaloids when they are fighting off parasitoids (probably against the set of maggots that have escaped encapsulation by the caterpillar’s immune system). The relationship between the ingestion of alkaloids, the immune response, and anti-parasitoid resistance is a current focus of study in my lab.

It seems like this would be a pretty easy feat for natural selection to accomplish (at least when thinking about it from a simplistic non-expert view, which mine most assuredly is). Some specific immune response could perhaps simply upregulate a few olfactory/gustatory receptors, for example. Or it could involve some more complex regulation of neural pathways controlling eating.

Carl, I am in awe of your ability to take what might on first glance seem rather uninteresting and instantly bring a deep potential connection to our own behaviors and experiences and give it greater context.

If the behavior above turns out to in fact link immune response directly with a relatively simple modulation of neural function or response, it wouldn’t be difficult at all to imagine similar phenomena in humans. I’d be interested to know if similar results could be found in any vertebrate. We all know that food tastes different (usually bland) when we’re sick, and we usually attribute this to stuffy noses and such. It would be quite fascinating to find out that certain foods become tastier…

great post!

Carl: James, thanks for your comments. I was thinking about mentioning the monarch butterflies, etc., in the post but then decided to stick to the woolly bears. Monarchs obviously also use chemical defenses, but they don’t eat extra milkweed when a flock of birds shows up. If you take a look at the paper, Singer and his colleagues explain how they view the woolly bear behavior as a plastic, adaptive response to infection–in other words, as self-medication.