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.”
