University of Minnesota Extension
www.extension.umn.edu
612-624-1222
Menu Menu

Extension > Garden > Insects > Giant water bug

Giant water bug

Jeff Hahn, Extension entomologist

Published in Yard & Garden Line News, May 15, 2000

giant water bug

Photo: Yard and Garden Line

Giant water bug

People from around Minnesota have been reporting a 2 to 2 ½ inch long, brownish insect with claw-like front legs. This insect is a giant water bug, Lethocerus americanus. If you examine it closely, you will notice a short, stout peak and fairly conspicuous eyes. A giant water bug is predaceous, feeding on other insects, tadpoles, and even small fish. Its front legs are raptorial, i.e. designed for grabbing and holding on to prey. A giant water bug is not aggressive towards people and is not considered a biting insect. However, if one is mishandled, it can administer a painful jab in self-defense.

A giant water bug is aquatic. It overwinters as an adult in shallow, muckish areas of ponds and lakes. The warm, dry spring has served to make giant water bugs quite active. Its overwintering sites have also been drying out encouraging this insect to take wing and look for a new habitat. This helps explain why they have been reported so commonly this spring. They are attracted to lights and it is common to find giant water bugs flying to yards, parking lots, ball fields, and other places lit by outdoor lighting.

This is strictly an outdoor phenomenon. However, there was one report recently of a giant water bug that had gotten inside and was found 'wrestling with the cat'. No control is necessary (just remove any that get inside by hand); this insect is just a curiosity.

  • © 2014 Regents of the University of Minnesota. All rights reserved.
  • The University of Minnesota is an equal opportunity educator and employer. Privacy