An online resource based on the award-winning nature guide

Insect Mouthparts

Robber Flies Capturing Prey

8-3-16  robber fly 009The robber fly family, Asilidae, is one of the largest families of flies.  All robber flies are predaceous and are recognized by their long bodies, forward-facing beaks and a tuft of hairs above the beak.  You find them on the ground or on leaf tips and other sunny spots where they survey the area for flying insects.  Once a robber fly has spotted a suitably-sized prey, it darts out and impales it with its stout beak.  It then inserts its needlelike “tongue” into the prey’s neck, eye or other weak spot, immobilizing the insect and liquefying its innards with an injection of saliva that contains nerve poisons and enzymes that break down proteins. Finally, it drinks its meal.  Pictured is a species of robber fly in the genus Diogmites, whose members are known for dangling by a foreleg while dining.

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Dragonflies & Damselflies Spear Prey With Lower Lip

7-27 dragonfly mouthpart 077Dragonflies and damselflies are unique among aquatic insect larvae in that they have a greatly enlarged hinged lower lip, or labium, which they can rapidly extend outwards to capture prey. When retracted, the prehensile labium fits like a mask over the face or is folded flat beneath the insect’s head. When hunting for prey, the dragonfly larva uses its labium like a speargun. It shoots forward as far as half the larva’s body length away, and moveable hooks on the front edge grab the prey. There are no muscles at the hinge/joint, leading entomologists to believe that the labium is extended by increased blood pressure caused by abdominal muscle contraction. It unfolds at a right angle, and extends extremely rapidly, faster than most prey can react. (photo: cast skin of dragonfly larva from which adult dragonfly emerged)

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