Back in January William and I took a walk at the Carpinteria bluffs, and saw that one of the big eucalyptus trees (Bluegum Eucalyptus, Eucalyptus globolus) along the Artists’ Passage had blown down in the wind. It was the easternmost tree, right where the path from the Bailard Avenue parking reaches the trees. The fallen tree was still there when I visited the bluffs today, and it actually seems to be doing okay for now; it’s at a steep angle, but the root ball seems to be more or less intact. I’m not sure if the city plans to do anything about it; I’ll have to ask Matt Roberts about that the next time I see him.

Toward the other end of the Artists’ Passage I noticed these interesting patterns in a fallen limb that had lost its bark:

I posted my photos to Bugguide.net, and Charley Eiseman (who else?) chimed in with some helpful pointers. The current consensus at Bugguide is that these galleries were made by the larvae of a species of cerambycid bark beetle, specifically, Phoracantha semipunctata, the Eucalyptus Longhorned Borer. That area in the upper picture where a bunch of small galleries diverge is where the beetle’s eggs were laid. As the larvae eat their way through the tree’s cambium layer they, and the galleries they make, grow larger, until you get the really wide galleries like the one in the lower photo. Eventually each larva eats a hole into the wood and pupates in it, before emerging as an adult beetle to repeat the cycle. I think that’s probably a pupation hole in the lower photo.

Like the trees they evolved to feed on, the Longhorned Borer is Australian. The Bluegum Eucalyptus trees were first brought to California from southern Queensland and Tasmania in the mid-1800s, and planted along the Southern Pacific Railroad lines as a source of lumber for railroad ties. According to Wikipedia, the railroad line that runs along the Artists’ Passage was completed in 1904, which I’m guessing is probably about the same time this row of trees was planted.

The beetles arrived in California in the 1980s, and have apparently become something of a pest. The galleries they leave behind are certainly interesting to look at, though.

Like the trees and the beetles, I’m not a native Carpinterian. I didn’t arrive here until 1995.

We entered on Estero Way, and worked our way out to the mouth of the marsh. Then we retraced our steps, and wrapped around next to the railroad tracks until we could walk out along the dike on the west side of the Santa Monica Creek channel. Toward the southern end of the dike there is a large patch of an invasive non-native with tall spindly stalks; Andrea tentatively ID’d it as black mustard (Brassica nigra). Here’s a shot looking past one of those stalks back toward the northwest:

I took that photo because Andrea had notice something interesting in the plant. Here’s a closer view:

It’s a collection of six spherical objects suspended in a loose web; Andrea’s guess was that they were spider egg sacs. Here’s a close-up:

There was one more interesting thing we noticed: Where the stem holding the spheres met the main stalk of the plant, there was a triangular structure that appeared to be made from the same silk as the web. You can see it on the left side of this picture:

Here’s a close-up:

We couldn’t find any spider to go with the putative egg cases, but after I got home I posted photos on bugguide.net, and within 15 minutes Charley Eiseman, co-author of the upcoming book Tracks & Sign of Insects & Other Invertebrates (which I can’t wait to buy) had ID’d the spheres for me. They are indeed the egg cases of a spider, specifically the Bolas spider Mastophora cornigera.

The spider is nocturnal; it hides in plain site during the day by looking exactly like a rounded bird dropping. (When I mentioned that to Andrea, she replied that she actually had noticed what she thought was a bird dropping on the plant not far from the egg sacs. I didn’t notice it at the time, and I can’t find it in any of my photos, unfortunately.)

The spider also has an interesting way of hunting: It dangles a strand of silk with a sticky ball on the end, and swings it with one of its legs to capture flying insects. The ball gives off a scent that mimics moth pheromones, and researchers have found that the spider can vary the scent over the course of an evening to appeal to different moth species that are active at different times of night.

Here’s a segment from David Attenborough’s Life in the Undergrowth showing M. cornigera hunting:

One mystery I still haven’t solved: What was that triangular silk structure at the base of the stem? I tried sending an email to Peter Bryant, a biologist at UC Irvine who has posted some neat photos of Bolas spiders on the web. I wrote him as follows:

I came across what I believe are some Mastophora cornigera egg cases yesterday at the Carpinteria Salt Marsh. I’m curious about one thing, though: There was an odd triangular structure, apparently built out of spider silk, at the point where the stem from which the egg sacs are suspended meets the main stalk of the plant. You can view a photo of the structure in relation to the egg sacs here:

http://bugguide.net/node/view/356752/bgimage

…and a closeup of the triangular structure here:

http://bugguide.net/node/view/356754/bgimage

At first I was thinking the structure might be a hiding place for the spider, but now that I’ve had some help identifying the species, and have looked at the wonderful photos you’ve posted of the adult female, I don’t think that structure would be large enough to hide one (and it doesn’t sound like they go in for that sort of thing, anyway, given their impressive bird-dropping mimicry).

I’m trying to figure out what purpose that structure might have. My lay speculation so far consists of:

* The aforementioned hiding place for the adult spider.
* A structural reinforcement, to prevent the weight of the egg sacs from causing the stem to break off the plant.
* A barrier to help prevent egg-sac predators from traveling from the stalk to the stem.

I’m curious if you know the answer, or would be willing to speculate. Thanks!

Dr. Bryant wrote me back, but unfortunately he didn’t have any ideas about that triangular silk structure. He suggested visiting the location again to see if the spider is nearby, which I’d love to do, but so far I haven’t had a chance (and I’d need to go with Peter, or someone else with official permission to enter that part of the marsh).

More Bolas spider links:

• Wikipedia article on Bolas spiders
• Bolas spider, Mastrophora cornigera – Interesting photos and captions by Peter J. Bryant.
• Science Spider Friday: The Bolas Spider! – by DailyKos user hekebolos

But no, it turns out this cricket was quite happy to let me locate and sneak up on him, and continued singing even as I got close enough (too close, it turns out) to snap this photo:

I say “too close” because the image is a little out of focus, something I didn’t notice until I got inside and uploaded the image to my computer. But by then I couldn’t go back and try for a better-focused shot, because while taking the above image I accidentally jostled a branch, causing him to stop singing and lower his wings (which are in their raised, singing position in that shot above). Here’s an even-fuzzier shot I got after he lowered his wings:

I got in trouble with Linda for making the cricket stop singing, and she forbade me to bother it any more; she’s still mad about it two weeks later. So that’s the best I can do, image-wise.

It turns out, though, that there’s lots of information about tree crickets (which is what this guy was) online; so I’ve since learned that this was probably either a snowy tree cricket (Oecanthus fultoni), which is found all through the lower 48 states, or a Riley’s tree cricket (O. rileyi), found only in the western states.

To tell the difference, I could have examined the little black markings in the first two segments at the base of the insect’s antennae. Or I could have carefully measured the temperature, and the rate at which the insect was chirping; Riley’s chirps are somewhat slower for a given temperature, while snowy chirps are somewhat faster. Snowy chirps also are faster in western populations than eastern ones, possibly because that helps the insects distinguish themselves from Riley’s.

I love the Internet.

Lots more about tree crickets is available at http://www.oecanthinae.com/, which apparently is the product of an amateur tree cricket lover who got bit by the bug (so to speak) fairly hard.

Finally, here’s 7 seconds of video of a male snowy tree cricket singing, courtesy of YouTube user TreeCricketFan, who may be the same hard-bitten obsessive mentioned above, or a different one; I’m not sure:

(Wikipedia image by Matthew Field.)

I’ve noticed this bee several times over the past few years: gigantic (bumblebee-sized or bigger), a beautiful golden color all over, with a habit of hovering for minutes at a time, pausing a few seconds in one place, moving a few feet, hovering again, and repeating, in a circuit that causes it to cruise a limited area over and over. Every time I’ve seen it engaged in this “hover patrol” it has been near some flowers being visited by ordinary honeybees, but I’ve never seen the giant golden bee actually land. I might be reading too much into it, but I get the impression that the bee is aware of me; it seems to face me and check me out, then decides I’m uninteresting and moves on.

I’ve seen this bee in our front yard in Carp, and outside the office building where I work in Santa Monica. (I’ve mentioned my ridiculously long commute, right?) Last Sunday William and I watched one patrolling outside some condos on Sandyland Road, as we walked from the State Beach campground (where we spent the night Sunday night) to the marsh and back.

I asked William what he thought the bee was doing. What’s up with that ceaseless patrol? It has to have a reason, I argued. The bee wouldn’t devote all that energy to the behavior unless there was some point to it.

I’ve tried to google for information about the bee before, without success. Today I tried again, and hit the jackpot.

The bee is the Valley carpenter bee, Xylocopa varipuncta. I’m used to seeing the female patrolling the eaves of houses and other wooden structures, looking for good spots to make a nest hole, and I knew that big black bee was a carpenter bee, but I never realized that this big golden bee was the male of the same species. An article from the UC Davis Department of Entomology quotes entomologist Lynn Kimsey as follows:

Carpenter bees, measuring about an inch long, are the largest bees in California. Their eggs are the largest of all insect eggs. The Valley carpenter bee egg can be 15mm long.

The males are territorial, Kimsey said, and can be quite aggressive. They hover and lie in wait for passing females.

“Female carpenter bees sting, but the males don’t have that apparatus,” Kimsey said. “You can pick up the fuzzy males and they won’t sting you.”

User INaturalist at bugguide.net posted this great image of the bee:

INaturalist wrote:

These big chubby guys come out in the spring and fly around in the willows where Coyote Creek flows into the percolation ponds. In Sunnyvale I find them in the Baccharis at the WPC ponds. They have a very short flight season — a couple of weeks and they’re gone. The females are black and yellow. This one is a drone — presumably its only function is to mate, so what is it doing patrolling? Waiting for a receptive virgin queen to emerge?

I think INaturalist’s speculation is probably right: The bee is on the lookout for females, and is patrolling a territory he’s staked out that seems likely to attract them.

So: Another mystery solved. :-)

The first thing we noticed at the marsh, though, was this tire near the northern Ash Avenue entrance. My guess is that someone just dumped it there, but maybe there’s more of a story behind it?

On the midge question, my (very rough) sense of things was that about half of the dozen or so galls I looked at had visible emergence holes. At one point while examining the terminal bud of a coyote brush (a bud that did not have a gall), I saw a small, black, winged insect climbing around, and I wondered if it might be a gall midge. It certainly looked fly-like, and was about the right size, judging by the emergence holes in the galls I’ve looked at. I tried to get a photo, but couldn’t get the focus right, and can’t see the insect in any of the shots I took.

A little more googling for information about the midge turned up an article from the Annals of the Entomological Society of America, titled Portrait of an Ephemeral Adult Stage: Egg Maturation, Oviposition, and Longevity of the Gall Midge Rhopalomyia californica (Diptera: Cecidomyiidae). Quoting from the abstract:

Observational and experimental studies in the field demonstrate that this midge typically completes its entire lifetime reproduction in a single day: females usually emerge at dawn, mate, and after a posteclosion period of resting, they initiate a sustained period of active oviposition during which most eggs are laid over a 4–5-h period. Mean longevity of adult females is very short, consistently <1 d and only 5–6 h on clear and warm days.

I had no idea the adult midges were so short-lived: The females emerge as adults from the gall with their eggs fully formed, mate, deposit their eggs, and die, all within a single day. I guess that means I have my work cut out for me in terms of finding an adult gall fly.

As often happens when I visit the marsh, the thing I went looking for wasn’t the most interesting thing I found. Instead, my big discovery was how clear the water in the Franklin Creek channel was. You could see all the way to the bottom across the whole width of the channel, and William and I had great views of fish swimming under the footbridge.

Here’s a shot I took that shows five fish swimming in a line from the bottom of the frame toward the top. They were about 18 inches long; I think they might be striped mullet (Mugil cephalus):

Obviously, when I talk about how clear the water was, I’m talking in relative terms. Normally I can’t see the bottom at all, or see fish that are more than a few inches beneath the surface, so this view qualifies as exceptional in my book.

I also got several shots of what I think was a round stingray (Urolophus halleri). The ray was about the size of a dinner plate:

Here’s another shot I got just as the ray was swimming into my shadow. Unfortunately, I didn’t include the entire ray in the shot, but this gives a pretty good view of its coloration, including the big, pale spots on its body:

I’m not sure why the water in the creek was so clear yesterday. We had some light, unseasonal rain last week; maybe that brought some fresh, relatively clear water into the creek channel? In any event, it was really neat to get a good look at what was going on under the surface.

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.

I’ve also seen them at the Carpinteria bluffs. (Thanks to William in both cases for pointing them out. Even though I was specifically looking for them, it took my perceptive 11-year-old to actually find them.)

The number of adult beetles on the coyote brush is still pretty small; I saw a few bushes that had 4 or 5 beetles climbing around in one area, but if the vast number of larvae I was seeing in the marsh a month or so ago is any indication, we’re due for a lot more beetles to appear in the weeks ahead.

There’s a new sign at the north entrance to the marsh, by the way. Wouldn’t this make a cool photo for Mystery Bird of the Day? Can you recognize the bird? It’s a common species in the marsh and on nearby beaches.

One of the first invertebrates I noticed at the marsh during my walk were these shiny green insect larvae, happily munching away on the leaves of coyote brush (Baccharis pilularis).

These guys were on every coyote brush I looked at; I count six of them in this picture alone. I did a quick estimate, and decided that there were about 500 of them on a single large plant. Multiply that by the amount of coyote brush at the marsh, and that’s a lot of larvae.

At first I thought they were some kind of caterpillar, but after posting my photo at bugguide.net, early speculation has centered on the genus Trirhabda, a kind of leaf beetle. Looking at this image of Trirhabda flavolimbata made me remember that several months ago I’d seen a beetle that looked a lot like that all over the coyote brush. According to this entry at bugguide.net, there are at least three species of Trirhabda in coastal California, with T. flavolimbata being the one that specializes in coyote brush.

Update: I took most of the photos in this blog entry during a walk with William on Sunday, March 29. Based on the discussion at bugguide.net, I went back this morning — Thursday, April 2 — with Julia to get some better photos. Here are three that she took (posted at bugguide.net here, here, and here).

This gives you a good shot of the larva’s head:

This shows the larva’s body, as well as a dark fluid on the plant that I’m assuming is related to the larva in some way, though I’m not sure how. Maybe it’s fluid that is draining from the fresh “frass” (insect poop) on the leaf above it?

In reference to that fluid, Charley Eiseman, author of the upcoming book Invertebrate Tracks & Sign, wrote in response to an email I sent him:

If these were caterpillars or sawfly larvae, I might be a little worried about their health, but more “soupy” excrement isn’t too unusual for leaf beetle larvae.

You know, I never expected when I got out of bed this morning that I’d be learning about the consistency of leaf beetle excrement. But I think it’s cool that the larva’s soupy poop actually helps confirm the ID.

Finally, here’s a shot that shows the larva’s prolegs. Some of the commenters at bugguide.net were especially interested in seeing those.

[Back to the original blog entry.]

While looking at the coyote brush, I also noticed this interesting white object:

I wasn’t sure at the time what it was, but I had a vague recollection that led me to google for “scale insect”, and sure enough, this looks a lot like a cottony cushion scale (Icerya purchasi) (and Charley Eiseman, writing at bugguide.net, agrees). Here’s a cropped version of the original image to give you a better look:

My google search led me to gardenbees.com’s Cottony Cushion Scale: The pest that launched a revolution in pest control methods. Among the things I learned there:

• This is a female scale insect.
• The actual insect is the brownish thing at the upper right, covered by white waxy fibers. She’s attached herself to the plant, and is more or less immobile.
• The large, white, grooved part extending to the left is not her abdomen, as I originally thought. It’s an external egg case.
• The cottony cushion scale is not native to North America. It hitchhiked here from Australia in 1868, arriving on a shipment of plants and soon becoming a serious pest in the California orange groves.
• The scale was eventually controlled by introducing one of its natural predators, an Australian lady bug. When I read that, it reminded me that I’d already read another account of that same event, in Sue Hubbell’s excellent book, Broadsides from Other Orders.

Continuing the list of things feeding on the coyote brush, I noticed this swelling at the end of a coyote brush stem. It’s a gall, the work of an insect that lays its egg inside the plant, leading the plant to create an enlarged chamber within which the insect larva grows:

I had no idea what insect might have done this, though Charley Eiseman responded at bugguide.net that he thinks it was made by a species of midge, Rhopalomyia californica. Looking at some of the other photos at bugguide.net, I think he’s probably right. I’ve been unable to find an image of the adult midge, but Flickr user “Eric in SF” opened up one of the galls and took a photo of the larva.

According to an article abstract I found online (Ecology of Rhopalomyia californica Felt at Jasper Ridge), the midge “is under investigation as a possible biological control agent against related species of Baccharis that are rangeland weeds in Texas and Australia.”

Another type of gall can be seen in this photo. These are in a leaf of the arroyo willow (Salix lasiolepis) growing next to the boardwalk that winds through the marsh’s small patch of coastal dune habitat:

Again, I had no idea as to the species of insect involved, but Charley Eiseman wrote at bugguide.net that he thinks it is a sawfly of the genus Pontania.

As I mentioned, the marsh’s patch of coastal dune habitat is small, but it’s very important to at least one species: the globose dune beetle (Coelus globosus), a coastal specialist that has become rare as coastal dunes give way to houses and condos. Andrea Adams-Morden has pointed out the trails in the dunes to me and told me they were produced by globose dune beetles, and I’ve seen a few dead beetles, but so far I’ve never found a live one. In the meantime, I like checking out their trails, which the beetles leave as they burrow just under the surface of the sand. Can you see the beetle trails in this photo?

Here’s a closeup of some beetle trails. It looks to me like maybe there was a single beetle that entered from the upper right, did a counter-clockwise loop, crossed its own earlier trail, and exited at the upper left:

There’s a neat series of photos of a related species, Eusattus dilatatus, at the myrmecos blog: Friday Beetle Blogging: Eusattus Dune Beetle. You can see the beetle burrowing into the sand, a process that takes about 30 seconds.

One of the best-known invertebrates in the Carpinteria salt marsh is the California horn snail (Cerithidea californica). Millions of these marine snails live in the marsh; you can see them crawling over the mudflats at low tide, and after they die their shells get washed out of the marsh entrance and turn up along the beach at Carpinteria, where I’ve picked up dozens of them during a single walk.

One of my favorite lectures during docent training was given by Dr. Kevin Lafferty, a parasitologist who has studied the use of horn snail parasites as a way of measuring ecosystem health in coastal marshes. I didn’t get any photos of horn snails during my walk in the marsh this past weekend, but I did take some photos of the very cool interpretive sign near the Franklin Creek bridge that talks about the complex life cycles of salt marsh parasites. Here’s a close-up of part of the sign:

If you want to learn more, you can see the image of the whole sign that I posted on Flickr, and click through to the largest size, which should be fairly readable.

One other invertebrate at the marsh, one that’s actually kind of similar to the California horn snail in size and shape, is the decollate snail (Rumina decollata). It’s a terrestrial snail, not an aquatic one. I noticed them crawling across the trail near Ash Avenue one morning when I was walking the marsh with William, and I was surprised, because I’d never seen an elongated snail like that on land before. An email to the carpmarshfriends Yahoo group got me some help with the ID, after which I learned more about the snail at the nice Wikipedia article on it.

Decollate snails are non-native; they originate near the Mediterranean, and are predators who feed on the eggs and young of other snails. They’re used by gardeners as a means of controlling another non-native, the invasive brown garden snail, and presumably that’s how these guys got into the marsh: crawling in from someone’s garden along Ash Avenue.

They’re nocturnal, and so far I’ve only seen them early in the morning after a rain. I couldn’t find any on my recent walk, but I did find this empty shell of one:

Update: When Julia and I returned to the marsh on April 2 to get better photos of the larvae on the coyote brush, we also found a decollate snail climbing in the blue-eyed grass (Sisyrinchium bellum). I really like this shot Julia took of it:

She also got this shot from the other side, showing what looks to me like a thread of some sort emerging from the area of the snail’s mouth. I didn’t notice it at the time, so I can’t tell you anything else about it, but it’s certainly interesting. What’s going on with that?

Thinking about it some more, and staring at the largest version of the image, I find myself thinking a wacky thought: What if the snail actually ate a spider? Could that happen? If it did, could it have left the spider’s dragline extending away from the snail’s mouth? I guess it’s a lot more likely that the snail decided to snack on a stray piece of silk, or just ran into it and got tangled up.

Overall, I had a really fun time rummaging for invertebrates at the marsh. I hope you enjoyed reading about them.