Friday Cat-erpillar Blogging: Tickling The Toes

Left: Prolegs of a Tobacco Hornworm with Crochets (hooks) used for gripping plant stems.  Right:  Tiny True Legs on the Thorax of a Tobacco Hornworm  Bottom:  A Catalpa Hornworm Supported By 3 True Legs and 5 Pair of Prolegs

Left: Prolegs of a Tobacco Hornworm with Crochets (hooks) used for gripping plant stems. Right: Tiny True Legs on the Thorax of a Tobacco Hornworm Bottom: A Catalpa Hornworm Supported By 3 True Legs and 5 Pair of Prolegs

Caterpillars use their prolegs to grip a surface tightly. At rest, a tobacco hornworm caterpillar will keep all prolegs firmly attached to the surface. The caterpillar can be induced to move its prolegs by touching a proleg with a brush. The caterpillar is ticklish. The progleg has hairs at the base of the proleg called planta hairs. The hairs are sensitive to touch and have nerves that connect to the ganglia (nerve center) in that segment. The nerve signal from the plant hairs is part of a reflex arc that causes the caterpillar to automatically withdraw the proleg and retract the crochets when touched. Why would a caterpillar retract its proleg? Perhaps it is an adaptation to touching by other insects such as ants? The reflex arc is sterotypic and of interest to scientists who study nerve reflexes.

About jjneal

Jonathan Neal is a retired Associate Professor of Entomology at Purdue University and author of the textbook, Living With Insects (2010). This blog is a forum to communicate about the intersection of insects with people and policy. This is a personal blog. The opinions and materials posted here are those of the author and are in no way connected with those of my employer.
This entry was posted in behavior, by jjneal, Caterpillar Blogging. Bookmark the permalink.

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