Posts Tagged ‘insects’

lies: Baccharis pilularis galls at Solstice Canyon, Malibu I…

Saturday, March 26th, 2016


Baccharis pilularis galls at Solstice Canyon, Malibu

I mentioned before that one of the things I enjoyed about Yulin’s beautiful I Didn’t Write This Ep. 2 (the one with Auden’s “As I Walked Out One Evening”) was the setting. They shot the video in Malibu’s Solstice Canyon, which I’d never visited before. It looked like there was some coyote brush (Baccharis pilularis) in some of the shots, but I wasn’t sure, and since yesterday was my once-every-two-weeks mega-commute via Malibu, I decided to check it out on my way to work.

I really loved it. There’s water in the stream year-round, and the riparian habitat along the main trail was super birdyish. I didn’t have my binoculars with me (which was just as well, or I probably would have been late to work), but the southern California nesting season is getting under way, so there was lots of singing. Yellow-rumped warblers, oak titmouses, California towhees, spotted towhees, and white-crowned sparrows were everywhere.

The upper slopes (which I didn’t have time to hike to) looked too xeric for coyote brush, but down near the creek there was a fair amount of it. It was more spindly than the plants I’m used to near Santa Barbara, and the seed heads on the female plants seemed a little less profuse; I suspect that’s because Malibu is warmer and dryer than where I live. There also was less coyote brush overall in the habitat; individual plants were scattered around, rather than occurring in extensive stands.

When I’m around coyote brush I always look for galls. There were relatively few Rhopalomyia californica galls compared to what I’m used to, but I found some that you can see in the middle row of photos above.

You’ll probably think I’m an idiot to feel this way, but I get choked up when I think about the midges that induce those galls. They spend most of their lives as tiny maggots inside the gall, feeding on plant tissue. Then they chew their way to the surface and pupate, their body liquifying before transforming into an adult midge, and then finally, on a particular cool morning, often a day or so after a rain, a bunch of them emerge together.

The females’ abdomens are already orange and swollen with eggs. The males mate with them and die; the females lay their eggs before dying a few hours later.

They live their whole lives for that one day. I’ve never seen a Rhopalomyia emergence in-progress, though I keep looking. Once I found a dead female a day or two after emergence, a sticky trail of eggs connecting her to the plant, dead in the very act of laying her eggs. Will my own life have a dramatic climax like that? Probably not. I’ll just get older and crankier, and eventually something will take me out. But that Rhopalomyia midge died a heroine, fulfilling the essential purpose of her existence in her final moments.

Besides the R. californica bud galls, I also found a couple of stem galls made by a moth, Gnomorischema baccharisella. You can see them in the bottom row of photos. A cool thing about these galls is how different the ecology of the gall itself is, compared with the similarly sized R. californica galls that grow on the same plant. The Rhopalomyia bud galls contain multiple larvae, but a G. baccharisella stem gall contains only a single caterpillar. The larvae in the bud galls don’t produce frass (insect poop). I’m not sure what happens to their waste; either they don’t emit any, or it somehow is excreted and carried away by the plant. That latter explanation seems kind of unlikely, but I don’t actually know much about insect/gall interactions, and over evolutionary time scales gall inducers and their host plants have evolved pretty complex relationships.

The caterpillar in the stem gall does produce frass, which accumulates inside the gall. When the caterpillar gets old enough it chews its way out and drops to the ground to complete its development. But now there is a convenient hole in the gall (you can see it in each of the galls pictured above, meaning both of those galls have already lost their original caterpillar), and a bunch of other organisms move in. Colonies of fungi grow on the frass, and fungus mites that eat the fungi, and other creatures that prey on or parasitize the mites. There are whole little worlds in there, and that’s just one type of gall on one type of plant.

When I give in to the temptation to talk about plant galls during docent tours at the marsh, someone usually asks about the nature of the relationship. Are the gall inducers harming the plant? Helping it? And what they’re really asking is, are these good bugs or bad bugs?

It’s an interesting question. Looking strictly from the perspective of the plant, the gall inducers are harmful. In parts of Australia, where groundsel bush (a close relative of coyote brush) is an invasive weed, R. californica has been imported as a biological control, because the bud galls take the place of flowers, reducing the plant’s reproductive success. In effect, R. californica harnesses the plant’s activity and channels it into producing more R. californica midges, rather than producing more coyote brush.

But the plant’s perspective isn’t the only one. From the point of view of the larger ecosystem, gall inducers are just doing what nearly every other organism has done before it: Finding a niche in the pre-existing biome within which it can survive, adding one more layer to the mind-bogglingly rich assembly of interrelated living things that make up all life.

From that perspective, what gall inducers do is awesome and cool. Certainly the fungus mites that specialize in living inside old G. baccharisella galls would say so, if you could ask them, as would the dozen or more species of parasitic wasp that prey on R. californica, or the hyperparasites that prey on those parasites, or the specialized bacteria that live in the guts of those hyperparasites, and so on, as far as human curiosity can take you. The more I learn about this, the more I believe that people like James Lovelock and the late Lynn Margulis were on the right track in arguing that we spend too much of our time focused on the organism as the most meaningful level of biological organization. We also need to think about life as a whole.

One other thing I liked about Solstice Canyon: Its parking lot was nearly full, but it’s a small lot, and the people who were there were really nice. I think the fact that it’s kind of hidden away on a side road means you’re only going to get people who make a point of seeking it out, and that selects for a certain kind of visitor.

At one point I was standing under a big sycamore, trying to see a woodpecker that I could hear drumming. Two people, an older woman and a younger woman who might have been her adult daughter, were standing not far away. I didn’t notice them paying any attention to me, but when I walked past them the younger woman asked me if I’d been looking for the bird.

“What?” I said, not because I hadn’t heard what she said, but because I’m shy, and a dork, and I’d been shocked out of my big-city bubble by a stranger willing to talk to me.

“Were you looking for the bird?”

“Oh, the woodpecker? Yeah. I couldn’t see it, though.”

“I’ll show you,” she said, and walked back a few feet to point it out to me, an acorn woodpecker that was hammering away at the underside of a dead limb.

“Thanks,” I said, and smiled, and she smiled, and we went our separate ways. And maybe it was just me being maudlin from thinking about Yulin’s video, which made me cry when I watched it — because of the music, and the images, and Auden’s words, and Sean’s delivery — but it just seemed like a really nice thing of that woman to do, noticing that I’d been looking for the bird, and helping me see it.

tl;dr: I had a really nice time at Solstice Canyon, and I’m happy I followed Yulin’s recommendation to visit it.

Originally posted 2014-02-11.

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lies: In which I see if I can make you nauseous with video of a…

Friday, March 25th, 2016


In which I see if I can make you nauseous with video of a green leaf beetle (Trirhabda flavolimbata) crawling around on a mostly-defoliated coyote brush plant (Baccharis pilularis) at the Carpinteria salt marsh. The beetles have been having an outbreak at the marsh for the last few months.

I think they’re cute, but even if you agree about that there’s still a chance of nausea due to my extremely poor cinematography, especially after I mounted the macro attachment to the iPhone and things got really shaky.

You can read more about these cute beetles (including blessedly stationary images) in the post I made earlier today.

Originally posted 2013-05-26.

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lies: Green leaf beetles (Trirhabda flavolimbata) at the…

Friday, March 25th, 2016


Green leaf beetles (Trirhabda flavolimbata) at the Carpinteria Salt Marsh

I mentioned previously that I’m a volunteer docent at the Carpinteria salt marsh. I started off being mostly into birds, but in the spring of 2009 I started obsessing about bugs, and it was these beetles that started that. I was looking for invertebrates to photograph for Circus of the Spineless, when I discovered that there were large numbers of shiny green “caterpillars” (I thought) feeding on the coyote brush (Baccharis pilularis) at the marsh. I estimated that there were more than 500 of them in a single medium-sized bush.

It turns out they were actually beetle larvae. Over the next several weeks I watched as they turned into adult beetles and kept munching. By the end of the outbreak, in late May, much of the coyote brush along Ash Avenue had been completely defoliated. The first two shots above are from that 2009 outbreak; they show the larvae (left) and an adult beetle (right).

By the next year the coyote brush had bounced back. There were only a few leaf beetles at the marsh each of the next three springs, but this year they’re back in a big way. Once again, a lot of the marsh shrubbery has been eaten down to bare twigs.

I was out there yesterday and today gathering data as part of a citizen science project that I’ll write up in another post, and while I was there I took some photos.

The second row above shows the effect the beetles have on the coyote brush. On the left is a plant that still has leaves (and beetles). On the right is one that’s already been eaten.

Finally, there’s a shot I took with the macro lens attachment I bought recently for my iPhone. It’s just a little dingus that slips over the end of the phone. I’m pretty impressed with how well it works, though I need to work on my focus skills. There isn’t much depth of field to work with.

Isn’t that beetle adorable?

I tried taking some video, too, which I’m in the process of uploading to YouTube. I’ll post a link to that when it’s ready, so you can see beetles in motion. (Update: As promised: shaky beetle video.)

Originally posted 2013-05-26.

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lies: California wild rose (Rosa californica) at the Carpinteria…

Friday, March 25th, 2016


California wild rose (Rosa californica) at the Carpinteria salt marsh

When I’m poking around at the Carpinteria salt marsh the thing that interests me most is the marsh ecology. I’m fascinated by the densely layered relationships of all those plants and animals; preying on each other and being preyed upon in turn, competing and cooperating, part of in an incredibly complex network of co-evolved interactions.

Here are a few photos I took recently in the patch of California wild rose (Rosa californica) that borders Ash Avenue. The flower at the top is not perfect, but its imperfections make it more interesting to me. I wonder what caused that damage to its petals.

Next are a couple of photos of a fungus I’ve noticed frequently in the marsh roses. It produces a bright orange fruiting body along the midvein on the underside of a leaf, causing the leaf to fold back on itself. A few years ago I asked Andrea Adams-Morden, head of the marsh docents and my go-to person for inane botanical questions, if she knew anything about this fungus, but all I remember is that she said it was a non-native rust, and she was hoping to have the plants treated to combat it. It made me sad to hear that, because I think it’s beautiful.

The next pair of pictures show some spiny leaf galls produced by a wasp, Diplolepis polita. The wasp inserts its egg in the leaf, and the rose responds by growing this outlandish, swollen, tumor-like structure, inside of which the wasp larva grows, feeding on the plant tissue. Gall researchers would love to understand better how this process works, but much of it remains a mystery. How do gall inducers manipulate their host plants’ normal growth pattern? What mechanisms are involved?

I’ve always assumed that the spikes on these galls reflect the wasp’s having taken advantage of the rose’s existing thorn-producing genetic code, appropriating it to better defend the gall from outside attack. And defending the gall is important: Just as the gall represents a successful exploitation of the rose’s resources, the gall itself is a resource that other organisms have evolved to exploit. As with most galls, the D. polita gall is prone to being targeted by other species, either inquiline species that feed on the gall tissue, or predators or parasites of the wasp larva the gall contains. There are even hyperparasites, wasps that lay their eggs in the larvae of wasps that laid their eggs in the larvae of the original gall inducer.

It’s kind of mind-boggling.

The galls darken as they age, eventually turning brown and brittle. The next photo shows what I believe is a younger gall, its spikes softer, more flexible; toward the middle of that photo two still-younger galls are just starting to emerge from their respective leaves. And in the lower right of the picture, something I didn’t even notice until after I got home and looked at the photo on my computer: A small female wasp, her long ovipositor resting on the leaf surface.

I’ve cropped in tighter on the wasp in the last image. It’s not a very good photo; I took these shots with my iPhone, and its built-in lens can only take you so far. I didn’t get any detail of the wing venation, which would have been really helpful for identification purposes. I’ve posted the image to, though, in hopes that a wasp specialist will be able to tell me something more. This could be a D. polita female, looking to lay her eggs in the leaf tissue to start more galls. Or it could be one of the other five species of inquilines and parasites known to associate with D. polita galls. Or it could be some completely unrelated wasp that just happened to be in the vicinity. I’ll probably never know.

Update: A helpful user on bugguide identified it as being a cynipid gall wasp, a category that includes D. polita. So given that it’s a female gall wasp hanging out on a leaf right next to a bunch of D. polita galls, I think the chances are at least decent that that’s what it is. Which is pretty cool.

Originally posted 2013-05-09.

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lies: Coyote Brush (Baccharis pilularis) through the year As…

Friday, March 25th, 2016


Coyote Brush (Baccharis pilularis) through the year

As promised, some photos of my favorite plant.

The first image was taken on March 28, 2010, at the Carpinteria bluffs. I actually was trying to photograph the March flies (Bibio albipennis) that were flying around the plant; there were thousands of them in mating swarms above the coyote brush at the bluffs that day. But I think it’s a nice shot that shows what the plant looks like when it has leafed out with new growth in the spring.

The next two shots show close-ups of the flowers of a male plant (left) and a female plant (right) when the plant is blooming in the fall. These shots were taken at the bluffs in September 2010. You can see how the unopened male flower buds are thicker at the tip, giving them a kind of “fat-headed” shape, while the unopened female buds are narrower at the tip. Once the flowers actually open the differences are more obvious, with the male flowers being disk-shaped and yellow with pollen, while the female flowers have long, white filaments.

The next shot is of a female plant in full bloom. I took this image on October 30, 2011 at the Carpinteria salt marsh. I like how it shows both the plant and the marsh at my favorite time in their respective cycles: The coyote brush looking like it has been dusted with snow, and the marsh at maximum high tide, with the pickleweed (Salicornia virginica) of the low marsh habitat completely inundated.

The next shot is a close-up of a female plant actually releasing its seeds. At this point just a little bit of wind is enough to carry the seeds away. I took that shot in November 2010.

The next shot was taken in January 2011 at the marsh. By then southern California’s wet season was in progress, and new leaves were growing. This shot shows an interesting “witch’s broom” structure in the plant’s old dead stems. I suspect that’s from an attack by a gall-inducing fungus called Pucinea evadens. Active P. evadens galls develop lengthwise fissures filled with bright orange spores. I have some photos of those I’ll share another time, but in this shot I like how the old dead stems are being gradually hidden away by the plant’s new growth.

Finally, I have a shot of a lone coyote brush plant taken in February, 2011. The plant’s vegetative growth phase continues, though it’s tapering off, leading into the long, dry, southern California summer, during which the plant stores up energy, preparing for the fall flowering. The marsh is at low tide, which makes for an interesting contrast with the earlier shot taken at high tide. This is the same basin as in the earlier photo, though this shot is taken from the east side of the basin while the other was taken from the north. But that’s the same patch of marsh in both shots, showing how dramatic the tidal changes are.

I haven’t talked much about the rich community of insects and other invertebrates that associate with coyote brush; I’ll save that for another post. But this gives you an idea of the yearly cycle of this plant that I love so much.

Originally posted 2013-05-08.

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