Identification, Images, & Information
For Insects, Spiders & Their Kin
For the United States & Canada
More goldenrod fauna, small galls

More goldenrod fauna, small galls
Pennypack Restoration Trust, Montgomery County, Pennsylvania, USA
July 10, 2009
Size: About 1.5 mm.
There are many of these small galls (in the center of a bunch of rolled leaves) some have little pupae inside; others are empty, especially the ones with a hole.
Two more:

A different one inside a similar gall:

More on Goldenrod Gall Fauna

Moved from Chalcid Wasps.

Moved from ID Request.

I have one in mind...
This gall looks like it is a blister formed by two leaves stuck together. Is that correct? Also, is the blister lined with white fungus on the inside? The gall is caused by a midge, although this pupa looks like it may be a parasitoid.

So many mysteries!
The blister seems to be made by two leaves stuck together or even three, in most cases. The inside of the gall is whitish and furry. Quite a few of the galls are empty or full of some messy debris. Most of the galls that have something have this type of pupa; I never thought that it would be a parasitoid because it fills the available space quite well. In my experience parasitoids are smaller than the hosts. A few of the other galls have the other type of pupa, evidently a different one; although my untrained eye didn't detect any difference between the galls.
I would have to start observing everything more carefully and documenting it with photos, starting with the species of goldenrod. I wasn't paying much attention to that either.

Asphondylia solidaginis
seems like a good match, so I've made a guide page for the galls. I left the pupa in ID Request since it appears to be something other than the gall maker. It's interesting how sometimes parasitoids can seem to be much more abundant than their hosts. I remember Bernd Heinrich suggesting that destroying promethea moth cocoons would help the species, statistically speaking, because more often than not, each one contains multiple cocoons of ichneumon parasitoids. Not something I would advocate, but an interesting concept to ponder, anyway!