What's That Bug? does not endorse extermination

have an infestation of bugs on my willow tree. They are dark gray with black spots and shaped kind of like a light bulb. The narrow part at the head. The back legs are longer than the front and they have little antennae. There are thousands clustered together. Can you tell me what they are and how to treat them?
Kim Kincaid
Aloha, OR

Hi Kim,
Sorry about the delay. I believe you have Giant Willow Aphids, Pterochlorus viminalis. This is a large species, reaching about 1/4 inch. It is gray with black spots, short black horns on the abdomen and a large tubercle in the middle of the abdomen. It feeds in large, compact colonies on the trunks and branches of willows often near the ground, and when disturbed has the habit of kicking the hind legs back and forth above the abdomen in a very energetic manner. This habit is common to all the individuals of a colony and is probably a means of warding off natural enemies according to Essig. Try your local nursery for a treatment. Here is a site with great information and photos.

What's That Bug? does not endorse extermination

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