Several midges induce galls on junipers. Unfortunately these juniper gall midges are confusing and their taxonomy has not been sorted out. Thus, especially for someone like me who is definitely not an entomologist, a genus classification must suffice.
Wandering the shores of Baum Lake (Shasta County CA) recently I noticed several types of juniper galls. One, “Juniper Witches’ Brooms“, I previously mentioned on 03-10-2014. Another, the juniper cone gall midge, belongs to the genus Walshomyia. This gall midge induces galls that resemble small cones on western junipers (Juniperus occidentalis) and several other juniper species. These galls are composed of overlapping bracts and occur singly or in clusters. When young, the juniper cone galls are a greenish color but turn brown with age.
The larvae develop within the gall and eventually, when mature, the adults escape through the tip.
In one of the cut galls the frass left by the midge and the exit route can be seen. The second cut gall appears to be newer with perhaps a larva still inside.