by Tony Hicks
Today, I took a photo of these little pests on the fir tree in the quad.
Aphids - from the genus Cinara - which feed on the sap of
the tree. They are host-plant specific and
tend to form colonies on individual trees. They secrete
honeydew, which is eaten by ants.
Cinara aphids are also called "Cinara conifer aphids" because they
attack a wide variety of conifers (pines, spruces, firs, etc.) and are
typically species-specific; i.e., a particular species of Cinara aphid will
attack a particular species of conifer. They only leave when the tree leaves.