Good housekeeping: why do shelter-dwelling caterpillars fling their frass?

[Cirsium]

Good housekeeping: why do shelter-dwelling caterpillars fling their frass?
Ecology Letters, (2003) 6: 361–370
Martha R. Weiss
Biology Department,
Georgetown University,
Washington DC 20057-1229

Here, I show that elimination of chemical cues for natural enemies is likely to have been a driving force behind the evolution of frass ejection behaviour in skipper caterpillars; hygiene and crowding are less important in this system.

Although both feeding and elimination of waste are imperatives for all animals, ecologists and evolutionary biologists have devoted considerable attention to foraging, while largely ignoring defecation. Many organisms, however, exhibit defecation behaviours that appear to have been shaped by natural selection in a range of ecological contexts. Accumulation of waste may pose particular challenges for animals that exhibit high site fidelity or live within enclosed spaces. In a taxonomically widespread but largely unexamined behaviour, many caterpillars that construct and inhabit leaf shelters ballistically eject their individual faecal pellets (frass) great distances at great speeds.

Within the family Hesperiidae, for example, larvae have been reported to shoot frass pellets a meter or more away (Frohawk 1913; Caveney et al. 1998); I have observed a 4-cm long Epargyreus clarus (silver-spotted skipper) larva launch a pellet a remarkable 153 cm, or 38 times its body length.

http://www9.georgetown.edu/faculty/e...x/ecollett.pdf


Flying frass - well, what can I say? As they used to say on one of the TV police shows "Hey - becareful out there!".

[Gloria]

I missed this somehow when it was posted. Very funny images come to mind.

[bridget1964]

LOLOL! And to think, people get PAID to research this stuff!

[ButterflyLinda]

I was raising the Goatweed Leafwing caterpillars and they fold a leaf over themselves. Two open ends, head toward the stem and they just let the frass fall out the hole at the tail end of the cat. I'd find a little pile of frass directly below the leaf nest. But I've seen other kinds of cats "fling" their frass with their tail end as it was coming out! Hey, if I could get someone to pay me to watch caterpillar flinging frass, that would be okay with me!

[NEWisc]

Flying frass - well, what can I say? As they used to say on one of the TV police shows "Hey - becareful out there!".

I'm thinking I might start using eye protection in the field ...