Acharia stimulea


Photograph by Al Denelsbeck.

Photography contest, Winner.

Our congratulations to Al Denelsbeck, the winner of the latest Panda’s Thumb photography contest with his remarkable photograph “Parasitized moth larva.” “Flightless cormorant,” by Dan Moore, was second. We will award Mr. Deneslbeck a book generously supplied by NCSE.


Acharia stimulea – saddleback caterpillar moth larva, which has been parasitized by a species of Braconid wasp, of the superfamily Ichneumonoidea. Mr. Denelsbeck writes, “Darwin, of course, made a comment in a letter to a colleague regarding the nasty life cycle of the Ichneumon family. The wasp has laid eggs in either the caterpillar itself, or in the eggs that would hatch the caterpillar, and the wasp’s larva hatched and commenced eating the caterpillar from the inside. Seen here, the larva have come to the surface and spun their cocoons outside the caterpillar’s body to pupate within, soon to emerge outside as adults. The caterpillar, already ravaged internally, will live only a few more days.

“Also of note is the normal appearance of the caterpillar, an example of aposematic coloration, or ‘keepaway’ signals. The spikes are assisted by a significant irritant, and the combination of the two traits serves to protect the caterpillar from predators such as birds; the irritant chases them off, while the coloration is memorable enough to form the association in the unlucky bird’s mind so they will not make another attempt on any member of the species. This mechanism, however, doesn’t impress the wasps.”


Unfortunately for the wasp larvae it is a moth caterpillar, not a butterfly caterpillar, so it doesn’t taste like butter.

Instead, it tastes like margarine.

Putting the “ick” in Ichneumonoidea for millions of years.

Glen Davidson

ksplawn said:

Unfortunately for the wasp larvae it is a moth caterpillar, not a butterfly caterpillar, so it doesn’t taste like butter.

Instead, it tastes like margarine.

It’s not nice to fool Mother Nature.

Bah! What has Nature ever done for ME?

ksplawn said:

Bah! What has Nature ever done for ME?

Spared you from the fate of that poor caterpillar. It may not seem like much, but I’ll take it.

Does today mark the start of national parasite week? PZ has a lovely (not) animated gif of a horsehair worm on what looks like a cricket.

Many thanks to those that voted, and of course Panda’s Thumb and the NCSE! Now we just have to get more of a turnout next time (instead of, you know, tilting at the windmills of creationist commenters so much ;-) )

More of the story, and some (cruddy) pics of the hatching, can be found at[…]ons-learned/

I had three accidental encounters with those spikes. They’re definitely irritating, that low grade sharp burning like a weak beesting that comes and goes for about 30 minutes - I imagine that it’s not pleasant at all when it’s in the mouth region (mine wasn’t, just to answer that question.) What’s curious is that it’s a bit delayed, not immediate - maybe 20 seconds or so before it really kicks in, which strikes me as being a bit too long for true effectiveness, but its presence in the species says it’s working better than nothing.

Thanks again!

callahanpb said:

PZ has a lovely (not) animated gif of a horsehair worm on what looks like a cricket.

Coming out of a cricket, actually.

My wife found four large green caterpillars on our tomato plants. Each was parasitized with many wasp larvae; otherwise we would not have seen them due to camouflage. My wife has a phobia of caterpillars, so it was my job to pry them off the plant and dispose of them. A disgusting job.

She says this will give her nightmares, and I’m not too happy about it myself.

It’s strange, but the longer this picture stays up, the less I see it as a creepy parasitic infection, and the more as the prize-winning visual composition it is. The cocoons themselves have kind of an orange sherbet color, at least in this lighting. If I didn’t empathize with the caterpillar, I might see it as a kind of exotic floral arrangement. I guess you can acclimate to almost anything.

I’m not even sure that it makes sense for me to feel empathy with the caterpillar. I wonder if I hadn’t read the caption, and wasn’t familiar with similar wasp lifecycles from popular reading, would I know that something is horribly wrong here (from the caterpillar’s perspective anyway)? There is still something diseased looking about it, but maybe I wouldn’t think so if it came with a different story. And I’m reminded of the tulips of the Dutch tulip bubble, that owed their exquisite variegation to viral infections. But, no, I don’t feel empathy for a plant, so that doesn’t creep me out. But an animal, even a caterpillar is another matter.

I guess if I think about it hard enough I can de-acclimate and go back to creepy.

To me it almost looks like an exotic coral reef in miniature.

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This page contains a single entry by Matt Young published on July 14, 2014 12:00 PM.

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