Western Conifer Seed Bug—Leptoglossus occidentalis

The western conifer seed bug has become a nuisance pest in many homes. The bugs enter buildings at the onset of cold weather in the late summer or early fall seeking a protected site to spend the winter. These bugs do not bite or sting, and will not damage the structure of your house. One exception is the occasional reported damage to PEX pipes sometimes used in plumbing and radiant heating systems (see Dig Deeper below). They have a pungent odor when handled and make a buzzing sound when they fly.

western conifer seed bug
western conifer seed bug
western conifer seed bug

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The adult western conifer seed bug is about 3/4 inch in length and is a dull brownish color. There is a faint white zigzag stripe across the midpoint of its upper surface. When the insect takes flight, it lifts the wings to reveal bright yellowish-orange areas on its back. It has long antenna, usually as long as its body. It has thick, flattened tibia on its hind legs. These insects are often mistaken for stink bugs as they produce an unpleasant odor when alarmed.

Control Information

In many instances, organisms that we deem "pests" may not be pests, and other organisms may only be pests in certain instances and control may not always be warranted. Usually, western conifer seed bugs are not considered serious pests and may occasionally be indoors in the winter months. There have been occasional reports of damage to PEX tubing (see Dig Deeper below). Recently, they have been found in Europe and are considered to be serious pests of conifers there.


Dig Deeper - Scientific Studies

More Information

[Photos, left to right: Whitney Cranshaw, Colorado State University, Bugwood.org; Joseph Berger, Bugwood.org; David Cappaert, Michigan State University, Bugwood.org]