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Western Conifer Seed Bug on tree needles
Western Conifer Seed Bugs © Dawn Dailey O'Brien, Cornell University, Bugwood.org

Western Conifer Seed Bugs

Residents of Massachusetts may see this large, brown—yet harmless—home invader come fall. First described in California in 1910, the Western Conifer Seed Bug (Leptoglossus occidentalis) quickly moved eastward. In 1956, they were reported in Iowa and in 1990 several were found in New York State. 


A true bug (order Heteroptera) in the family Coreidae, the dull-brown Western Conifer Seed Bug is known as leaf-footed bugs because of a flattened segment resembling a leaf on their hind legs. As a defensive mechanism when alarmed or handled, the Western Conifer Seed Bug omits a pungent odor from glands between the second and third pair of legs.

They are sometimes considered a "stink bug" due to the pungent odor they emit when alarmed, handled, or smooshed.

Life Cycle

The female lays rows of eggs on the needles coniferous trees (hence the name), including white pine, red pine, hemlock, and spruce. Eggs hatch in about 10 days and the nymphs feed on the scales of the cones and occasionally the needles. They reach adulthood in late August. 

In the fall, the Western Conifer Seed Bug enters buildings through cracks and crevices searching for protection from cold temperatures. Read on to find out what to do if you encounter one indoors.

Situations & Solutions

Even though they are harmless to people and do not sting, bite, or eat wood, these bugs may cause concern. They are good but noisy flyers and can sound like a buzzing bumblebee.

Western Conifer Seed Bugs in Homes

  • Prevent the entry of Western Conifer Seed Bug by calking openings around windows, doors, and chimneys; repairing damaged window screens; and screening attic and wall vents.
  • These bugs can be easily captured and returned to the outdoors or vacuumed into a bag and disposed of. There is no need to resort to insecticides. Chemicals are dangerous—Western Conifer Seed Bugs are not.