a fossil spruce gall

Mystery Fossil #54

Though it looks like a pine cone, this is a spruce gall, produced by an aphid-like parasitic insect called an adelgid (family Adelgidae, order Homoptera). The galls are formed through the introduction of the insect's saliva into the host plant, causing changes in the plant's development. This particular spruce gall is from the Miocene Mascall Formation of Grant County, Oregon. Read more about a modern spruce adelgid and its fascinating life cycle here.


Credits button UCMP logo Copyright symbol