The primary diet of this species is the soft seed of pine trees, Douglas firs and other cone-bearing trees (hence 'conifer' in their name). They also eat the buds of cones and new needles. They pierce the tender plant parts and suck them dry. This had led to a diminished seed supply in forests, meaning fewer conifer trees are sown that season and new tree growth decreases in that area. This is another reason why the Western Conifer Seed Bug is considered a pest. Many of the conifer trees they eat from are also used by people for lumber and Christmas trees.
A type of Leaf-Footed Bug, Western Conifer Seed Bugs have long bodies and wide, flattened 'thighs'. This species has small spikes on the upper hind legs and a light, white marking across the elytra (wing covering). They are flying insects and are known to buzz while in flight, which can make them easier to find. The bright yellow and black contrasting bands along the sides of the abdomen are highly visible in flight and may lead an observer to first think it is a bee. Like other Leaf-Footed Bugs, it can emit an odor when threatened or crushed; this one's is likened to the scent of pine.