Thursday, July 12, 2012

Looking like Crap

This is not necessarily a bad thing, certainly not when you are a potentially tasty meal surrounded by dozens of predatory species often much larger and faster than yourself. In the unforgiving realm of nature the demands of survival take precedence over vanity, and unlike we, the people, insects don't have the luxury of worrying about the latter, their only goal is to live at least long enough to pass on their genes to the next generation.

A Small Bird-dropping Moth (Ponometia erastrioides) ... the name says it all. The usual color scheme is a mottled mixture of white with reddish-brown and/or black, combined with a lumpy irregular profile.

Schlaeger's Fruitworm Moth (Antaeotricha schlaegeri)

A mating pair of Pearly Wood-Nymphs (Eudryas unio)

White Banded Fungus Weevil (Eurymycter fasciatus)

A winged adult insect can always take flight as a last resort if the poop ploy fails. Larvae don't have this option and many strive look even more convincingly like bird droppings, such as this Giant Swallowtail (Papilio cresphontes) caterpillar which comes complete with a glossy finish.

Should relatively small predators such as ants or spiders persist in their attentions the caterpillar has a secondary line of defense, the osmeterium, the "horns" seen in the following two photos. This gland is covered with a repellent 40:60 mixture of isobutyric acid and 2-methyl butyric acid – thus saith the various sources on the Internet, I didn't have my chemistry set with me.

Faking a piece of crap isn't solely about color, attitude and posture are also important. This White Admiral (Limenitis arthemis) larva curls its front end to imitate the appearance of a bird dropping. Hopefully this "ugly duckling" will live long enough to pupate and eventually metamorphose into an adult.

Although very different in appearance the Viceroy (Limenitis archippus) is closely related to the White Admiral. (The quite palatable Viceroy is, of course, mimicking the toxic Monarch.) Except for the brown being replaced by a grungy green the caterpillars definitely resemble one another – as well as bird droppings. Also note this caterpillar's posture – feeling threatened by my presence, it is keeping its head down while holding its convincingly head-like non-vital tail end in the air ... just in case its crappy camouflage fails ...

The larval stage of Tenthredo grandis, a species of Sawfly (order Hymenoptera) related to the bees and wasps. Is this pattern meant to fool a hungry bird, or does it serve some other purpose? It is somewhat too regular when compared to the butterfly larvae above, but who knows, maybe its good enough.

And I've always wondered about the pruinosity on a male Chalk-fronted Corporal (Ladona julia). These dragonflies prefer to perch in open sunny places on the ground. Are those chalky white markings meant to look like splats left by a passing bird?