Gardeners often think of caterpillars eating their plants because almost all of the over 150,000 or so species of caterpillars eat plants. However, an odd assortment of about 200 caterpillars do not eat plants. They are predators on other insects or small animals. One fascinating predatory caterpillar is, Hyposmocoma molluscivora. As its species name, molluscivora suggests, this caterpillar eats molluscs, primarily snails.
The snail feeding habits of Hyposmocoma molluscivora were described in an article in the journal, Science, by Daniel Rubinoff and William Haines (Science 22 July 2005:
Vol. 309 no. 5734 p. 575 DOI: 10.1126/science.1110397 ). A student found the snail-eating caterpillars on the Hawaiian island of Maui and brought them to entomologist, Daniel Rubinoff. Rubinoff thought the student must be mistaken and first tried other foods on the caterpillars. They did very poorly until snails were placed in the container with the caterpillars.
Hyposmocoma molluscivora caterpillars will not attack moving snails. The caterpillars wait until they contact a snail that has stopped moving. Then the caterpillars vigorously spin silk threads to tie the snail to a plant leaf and immobilize the snail. At this point the snail cannot escape. The caterpillar enters the snail shell through the opening and feeds on the snail inside its shell. Sometimes the caterpillars will attach an empty snail shell to the silk case that the caterpillars weave around their body. The snail shell may provide protection against other predators.
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The caption under the picture should really have a hyphen therein: “snail-eating” instead of “snail eating”. That would make it easier to see who’s eating whom.