Hawaiian caterpillars hunt like spiders:
‘Although all caterpillars have silk glands, this predatory caterpillar uses silk in a spiderlike fashion to capture and immobilize prey,’ Daniel Rubinoff and William Haines at University of Hawaii wrote in their report.The caterpillars of the newly described species, Hyposmocoma molluscivora, are small — about a third of an inch (8 mm) long. Wrapped in their cocoons, they ‘lumber along’ leaves, Rubinoff and Haines said.
‘The caterpillars do not eat plant foliage, even when starving,’ they wrote.
Instead, they hunt Tornatellides snails.
When they find one, ‘they immediately begin to spin silk webbing attaching the snail shell to the leaf on which it rests, apparently to prevent the snail from sealing itself against the leaf or dropping to the ground,’ the researchers wrote.
‘The larva (caterpillar) then wedges its case next to or inside the snail shell and stretches much of its body out of its silk case, pursuing the retreating snail to the end of the shell from which there is no escape. We observed 18 attacks by 10 different larvae following this sequence.’
Sometimes the caterpillars decorate their silk casings with empty snail shells, probably as a form of camouflage, the researchers said.
The caterpillars eventually become small moths.
The researchers say they are surprised by the findings and note the caterpillars join a range of unusual Hawaiian fauna, including spiders that impale their prey in flight.
‘Caterpillars and terrestrial snails co-occur widely on all the continents where they are present, but only in Hawaii have caterpillars evolved to hunt snails,’ they wrote.