Posted June 2nd, 2009 by John Callender

I was walking at the Carpinteria Bluffs with William the other day, and noticed this on a coyote brush:


I think it’s an old, dried-out bud gall from the same midge I mentioned previously, Rhopalomyia californica. I like that you can see what I assume are the holes made by the adult midges when they emerged from the gall. I’m curious what the adult insect looks like. I’ve tried googling for images of it, but so far I haven’t found any. At least I have an idea of how big they are: just big enough to squeeze out of those holes.

Here’s an image I did find: Blogger user Raphael posted it in an item about wetland restoration at Shoreline Park in Long Beach:


This gall, which is still on a living plant, shows the same emergence holes as my dried version. I wonder what it looks like when the midges emerge. Do they all come out at the same time?

I’d really like to see that some day.

Update: They do emerge together. Check out this amazing series of photos taken by Charles Baughman on March 28, 2010, of a bunch of adult Rhopalomyia californica emerging in Boulder Creek in Santa Cruz County: Coyote Brush Bud Gall Midge – Rhopalomyia californica.

Later update: I take back part of what I wrote above: I don’t think those photos by Charles Baughman show adult midges emerging. I think they show the spent exuviae left behind after the emergence. Still beautiful and amazing images, of a phenomenon I’d still love to see firsthand. As I write this, at the tail end of 2010, we’re coming up on R. californica emergence season. I’ll make a point of checking those galls over the next several months, and see what I can find.

One Response to “Emergence”

  1. […] Russo talks about several gall-forming invertebrates of my favorite plant, coyote brush (Baccharis pilularis). One of them is the coyote brush bud gall midge, Rhopalomyia californica. I wrote previously about finding this old, dried-out R. californica gall: […]

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