September 11, 2009
A Choked Chokecherry
When riding along Mill Hollow in Indian Canyon, we saw a bush that had chokecherry leaves, but the berries were not round, as in the photo above.
Instead, the berries were oblong:
At first, we though this was a different plant. Then Steve cut open one of the berries and found:
these weird little worms. Upon further research at home, we found that these are chokecherry gall midge larvae. (Contarinia virginianae)
The chokecherry fruit gall midge is a tiny fly that causes direct damage to the fruit. Adults emerge from overwintering pupae in late May and lay their eggs in the flowers. Tiny yellowish-orange maggots feed on the developing fruit. As feeding continues, the developing fruit becomes enlarged (gall) and the developing seed aborts. Larval feeding continues until late July, when the larvae drops out of the gall to the ground to pupate. The hollow, damaged fruit will often drop off before the berries are ripe.
Feeding by the larvae causes a gall to form. The gall is the enlarged fruit, which is pear-shaped and hollow. There may be a combination of normal berries and galls on the same fruit cluster. Initially the gall is green in colour but changes to red as it develops. -- http://www.gov.mb.ca/agriculture/crops/insects/fad69s00.html