Definition of Thigmotaxis

Earwig, Dermaptera, Victoria, British Columbia, Canada, Canada
Jared Hobbs / Getty Images

Thigmotaxis is an organism's response to the stimulus of contact or touch. This response can be either positive or negative. An organism that is positively thigmotactic will seek contact with other objects, while one that is negatively thigmotactic will avoid contact.

Thigmotactic insects, like cockroaches or earwigs, may squeeze into cracks or crevices, driven by their preference for close quarters.

This behavior makes it tough to eradicate some household pests, as they can hide in large numbers in places where we can't apply pesticides or other treatments. On the other hand, roach traps (and other similar pest control devices) are designed to use thigmotaxis to our advantage. Roaches crawl into the small trap opening because they're looking for a tight-fitting refuge.

Thigmotaxis also drives some insects to aggregate in large numbers, particularly in the cold winter months. Some overwintering thrips seek shelter under tree bark, crawling into crevices just a fraction of a millimeter wide. They will reject shelter that is otherwise suitable if space is deemed too large to provide the contact they desire. Lady beetles, too, are driven by the need for touch when forming overwintering aggregations.

Scale insects, guided by positive thigmotaxis, will cling tightly to any substrate under them, a behavior which keeps them fastened to their host plant.

When flipped on their backs, however, this desire drives them to grab hold of anything within reach, in a desperate and sometimes futile attempt to keep their bellies in close contact with the world.

Sources:

  • Encyclopedia of Entomology, edited by John L. Capinera.
  • Encyclopedia of Insects, edited by Vincent H. Resh, Ring T. Cardé.
  • Journal of Economic Entomology, published by the Entomological Society of America, 1912.
  • The Ecology of Insect Overwintering, S. R. Leather.
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Hadley, Debbie. "Definition of Thigmotaxis." ThoughtCo, Apr. 5, 2017, thoughtco.com/thigmotaxis-definition-1968579. Hadley, Debbie. (2017, April 5). Definition of Thigmotaxis. Retrieved from https://www.thoughtco.com/thigmotaxis-definition-1968579 Hadley, Debbie. "Definition of Thigmotaxis." ThoughtCo. https://www.thoughtco.com/thigmotaxis-definition-1968579 (accessed January 23, 2018).