Those little sleeping baggy moth things that hang from twigs or the the weather boards of your house, they're just pupae of a moth, right? They'll emerge and fly off, leaving their case hanging empty, just as other moths and butterflies do.
Well, no. They aren't and won't.
This picture I took of a female case moth is evidence that the case and moth are part and parcel of a curious beast that crawls about, cleaning up the place. The female case moth nibbles on goop that forms on walls, paths and presumably the trunks,branches and twigs of shrubs and trees. She doesn't ever leave her bag willingly, is mated by the male moth through the opening in the base of the bag and lays her eggs through the same aperture. Or so I believe. Correct me if I'm wrong.
Ruud Kleinplast and Paul Gay would probably go apoplectic if they read this amateur entomological account but it should be enough to settle a debate I've been having with one of my readers :-)
2 comments:
Yes and no they are, and yes and no they will! Undergrad zoology and google combine to thread this reply :)
This wee worm is the larvae of a moth of the Family Psychidae - the case or bag moths. The larvae walks around in the case, eating mostly leaves, and hangs vertically encased when resting. There is probably a handful of larval instars, likely 5-7. As they grow they expand their cases from the head end, adding as they go. They do this by cutting off appropriately-sized twigs, attaching them temporarily to the top of the case and then disappearing inside to cut a slit where they plan to attach the new stick. This is no mean feat. Case moth cocoons are incredibly tough; cutting a slit for a new stick can take over an hour!
Case moths spend most of their lives in the caterpillar phase; this part of their life cycle can last 1-2 years. As caterpillars, they never leave their cases, though they can be very mobile, dragging their large cocoons along as they move around. If they feel threatened they can seal off the end of the cocoon, cutting a new opening once the threat has passed. The females continue to live in their cases after they’ve pupated into adult moths, but the males leave their cases after pupation to fly off in search of females.
Damn they're cool!
Ah! Great researching there Nick!
There are males in some of them - that I didn't know! The whole mating-with-a-sleeping-bag thing must look hilarious.
Do the females, having metamorphosed into an adult, have wings? I'd imagine not but who but an undergrad zoologist would know!
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