Western Conifer Seed Bug (Leptoglossus occidentalis)

Western Conifer Seed Bug (Leptoglossus occidentalis)


The Western Conifer Seed Bug (Leptoglossus occidentalis) is a true bug (Heteroptera) in the Leaf-footed Bug Family (Coreidae) and order Hemiptera. This bug originated in the warmer parts of the Northwestern United States but has spread to the Northeast and is considered an invasive species in some parts of Europe. During late fall and early winter, this bug seeks a warm place to hibernate. Warehouses and homes are attractive hibernation areas. It prefers cracks and crevices in which to hibernate. Therefore, the Western Conifer Seed Bug has become an unwanted visitor transported by shipping crates and parcels. These bugs move slowly with their legs but are good flyers during which they make a buzzing noise. If handled, they may emit a foul smell and may harmlessly stab with their proboscis. Generally, they are harmless although the noise they make in flight may be annoying.

These bugs can grow to a length of over one inch (2.5 centimeters) but the average length is shorter with the males slightly smaller than the females. The coloration can vary but they are generally reddish brown to dark brown. Like other Leaf-footed Bugs, the hind tibia is shaped like a leaf as seen on the upper hind leg in the photograph above. The lower, hind leg in the photograph is turned to provide a side view of the hind tibia. However, the inside and outside of the hind tibia in the Western Conifer Seed Bug are of nearly equal length, which is not true of the closely related Leaf-footed Pine Seed Bug (Leptoglossus corculus). The Western Conifer Seed Bug also has alternating dark and light bands on its outer wing edges near the abdomen as seen in the photograph above. They have a pair of large compound eyes as well as a pair of simple eyes towards the front of the head. The antennae also have four distinct segments.

Western Conifer Seed Bugs feed on conifer seeds of the White Spruce, Eastern White Pine and Red Pine. However, they are generally not problematic unless they infest commercial conifer stands. They lay eggs in small groups on pine needles or stems. These eggs hatch in the spring and produce nymphs that go through five metamorphisms before becoming adults.

A large number of these insects may invade a home in the fall. However, homeowners may notice only a couple. They are easy to catch and can be released outdoors. Western Conifer Seed Bugs will do no harm indoors and will go outdoors in the spring.

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