Earlier this week, I found myself in the field surrounded by sagebrush with more galls than I’ve ever previously seen. It seemed every plant had at least 50 to 100 small grape-sized galls. Their reddish and green color scheme had been bleached by the sun, turning them a sallow gray, their texture noticeably drier and almost papery compared to a month earlier. While going about my work, I was unconsciously brushing numerous flies away from my clip-board, arm and face, and each time, getting progressively agitated. One fly, haughty enough to land on my arm, met his demise right before I pieced together the blatant reason for abundance: Lots of galls! Those flies sure had some gall(s)…sorry I couldn’t resist. It would seem the onset of summer initiates the emergence of the flies, ending any exogenous chemical contribution from insect to plant maintaining the gall structure, which would explain their physical change. Of course, that’s just my guess. Sounds convincing enough…but why was that location overrun with so many galls?
(one of the pestering flies)
(this is a really tall sagebrush. the pole in the picture is 1M long)
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