University of Maryland Extension

Predators - Assassin Bugs

assassin bug

Brightly colored assassin bug

wheel bug

Wheel bug (type of assassin bug)

immature assassin bugs
Assassin bug nymphs

Assassin bugs are generalist predators that feed on a wide variety of pests ranging from small ones like aphids to larger ones like caterpillars. These patient hunters may either stalk their prey, or quietly wait for an appetizing insect to cruise by, then suddenly attack with their dagger-like, piercing-sucking beak. Assassin bugs are generally larger and have longer legs than most other bugs, and have beady round eyes well suited for spotting prey. They are important predators in the home garden, but handle them with care as large species will bite humans as well as their prey! There are over 160 species of assassin bugs in North America, most of which survive the winter as adults in sheltered locations.

Important species in Maryland: Spined assassin bug, wheel bug, elongate assassin bug.

Life stage(s) that feed on pests: Nymphs and adult.

Insect(s) fed on: Aphids, leafhoppers, asparagus beetle eggs and larvae, small flying insects, and up to medium-sized caterpillars. Some species in the genus Apiomerus hunt and eat bees.

Appearance:
Eggs: Laid in tight, upright clusters on bark, leaves, or in soil.
Nymphs: Resemble smaller, wingless adults.
Adults: Moderately large (usually 1/2 to 3/4" long; wheel bug may be up to 1 1/4”); most have a long, narrow body, with a long narrow head and a distinct “neck”; all have a pronounced “snout” with a long needle-like beak carried tucked up beneath the body; usually brownish, blackish, or gray (some elongate assassin bugs are bright green or red, with dark markings). The wheel bug has a distinctive semicircular crest, or “cogwheel”, on the upper back.

Where to find: Most garden plants, field crops, ornamental trees and shrubs. Spined assassin bugs are often found on goldenrod and other wildflowers.

How to conserve: Avoid use of broad spectrum insecticides. Plant flowers and plants that attract a variety of other insects.

Contributors: Mike Raupp, Jon Traunfeld, and Chris Sargent

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