A running joke in my family these days is that I have a crush on coyote brush. We were playing “20 Questions” at the dinner table a few nights ago (anything to get William beyond grunting), and when it was my turn to choose and I announced, “vegetable,” William got it in one, asking with a roll of his eyes, “Is it coyote brush?”
Sigh. I can’t help it. That plant is just so cool.
I previously wrote about the infestation by what I believe was orange tortrix (Argyrotaenia franciscana) along the trail below the Sidenberg Overlook at the bluffs. The infestation was really bad for a while, but the plants have bounced back. Coyote brush has co-evolved with A. franciscana over a very long span of time; apparently the occasional infestation is no big deal. The same plants that basically had no healthy-looking foliage at all two months ago now look like this:
We’re reaching the end of the flowering season for coyote brush, and some of the female plants look like they’re covered in snow. Here’s a closeup of some seeds getting ready to set sail:
When you start paying attention to coyote brush, you can’t help but notice the great variety of insects that associate with it. Here are some photos I’ve taken lately.
Bob Carlson, a retired entomologist who previously did postdoctoral work studying Ichneumonidae, was nice enough to comment on these images I uploaded to Bugguide. He thinks the bluish tint to this small wasp’s eyes suggest that it might be a male (because it lacks the female’s long ovipositor) of the Agathidinae subfamily:
Here’s another wasp, this one crawling around on a Rhopalomyia californica bud gall. It’s not a great photo, but I’m wondering if this might be a species of Torymus, a group of parasitoid wasps that prey on the larvae of gall midges.
No luck so far on an ID for this fly, but after I posted its image at Bugguide and asked for any ideas about what was going on with that bubble of liquid coming from the fly’s mouth, I got a pointer to this interesting discussion: tiny bubbles.
According to my copy of Russo’s Field Guide to Plant Galls of California and Other Western States:
Coyote brush (B. pilularis), also called chaparral broom, is one of the most interesting shrubs entomologically. Tilden’s monumental study (1951) of this shrub identified over 221 species of insects associated with it, as well as eight species of mites. The insects, in turn, hosted an additional 62 species of parasites for a total of 291 species on coyote brush…
As mentioned earlier, the intricacies of host plants, gall inducers, parasites, and inquiline relationships, especially as exemplified by the coyote brush regime, are vastly complicated and a worthy subject for additional study in the future.
You hear that, scoffers? “A worthy subject”!
The Tilden referred to in that passage is James Wilson “Bill” Tilden, who passed away in 1988. He did his 1948 doctoral dissertation at Stanford on the insect associates of B. pilularis. The dissertation was 408 pages long, according to this obituary published in the Journal of the Lepidoptrists’ Society: James Wilson Tilden (1904-1988): A Remembrance (PDF file). I’d love to get a copy of that dissertation.
Not quite as long, but still very much a current object of my desire, is the “monumental study” Russo refers to, Tilden’s 1951 paper, “The Insect Associates of Baccharis pilularis De Candolle”. It was published in Microentomology, a journal that hasn’t yet made it onto the Web, unfortunately. The paper is 39 pages long, and according to a reference I was able to google up, they have a copy at the UCLA Biomedical Library. I think I’m going to have to pay a lunchtime visit to Westwood during one of the days when I’m working in Santa Monica.