Category: spiders

Spider sprays strands of silk

September 26, 2023 • 1:15 pm

I’m itching to do biology posts, and have at least one or two papers on my desk, but of course those are the hardest posts of all and get few comments. Nevertheless, I’m proceeding, but every day I get about eight or none political posts that are less work.  Well, I do my best.

In lieu of a real science post, here’s some natural history by David Attenborough, showing a spider that can put a web 2 meters across hung 25 meters across a river.  (Rivers, of course, are good places to catch insects. What always amazes me about spiders is that their brains are so small yet are complex enough to encode very sophisticated behaviors, including weaving webs of intricate and reproducible shape.

This spider has a different skill set, but still as amazing.

Readers’ wildlife photos

August 7, 2023 • 8:15 am

Well, folks, this is the last substantive batch of photos I have in the tank. If you want more this week, you’ll have to provide them. These come from our most regular regular, Mark Sturtevant; his captions are indented and you can enlarge the photos by clicking on them.

This post has been on my mind for several years, beginning with an encounter that I had with a weird little fly on a bridge. Here is that fly (I think Pseudotephritina sp.), and I had probably shared it here once upon a time. It was marching up and down on the bridge rail while continually waving its wings. I did my best to photograph the little insect, which was no bigger than a fruit fly, with my little 50mm lens on extension tubes. But I wasn’t the only one interested in the fly. There was also a jumping spider, and it definitely was intent on having the fly for a meal! As the spider stalked closer, the fly would suddenly turn to it, waving its wings, and the spider would flee! This was repeated several times until the spider gave up. Did the stripes on the wings look like spider legs to the jumping spider? Jumping spiders do signal to each other by waving their legs. This is how they avoid conflict.

Now one must not make too much of this impression from a one-time encounter like that. But many flies in several different families have boldly patterned wings which they wave around. While this is known to act as intraspecific communication, it is thought that in at least some species flies also use this kind of display to scare off free-roaming spiders like keen-eyed jumping spiders. There is, for example, a classic paper concluding that another fly, Rhagoletis zephyria, would frequently display its patterned wings when stalked by jumping spiders, and spiders would tend to stop their approach in response. Here is a picture from that study, and one can definitely see that the fly does look like a jumping spider:

R. zephyria is part of a large species complex of flies that all strongly resemble each other. From the BugGuide web site, I count 18 species in North America. One of these is the apple maggot fly (R. pomonella), and I do have two apple trees and I see what I presume is that species of fly in the yard from time to time. It should be mentioned that the apple maggot fly is also a classic example of sympatric speciation, since the flies originally relied on hawthorn trees as their host. [JAC: the idea that the two host races of this fly formed sympatrically is probably not correct; see Coyne and Orr 2009). But with the introduction of apples into the country, some of them jumped to apple trees and there is now significant reproductive isolation between the two populations. Anyway, one of the flies appeared on my back porch last summer, and because I was able to catch it I could at last act on what has been on my mind for many years. Would this fly use its wings to deter a jumping spider? Mind you, this is a different species from the one described above, but … maybe? The following pictures record the results of this admittedly informal attempt to test that hypothesis.

Here is the fly, feeding on slices of sour green apples. It was quite content to just sit there and feed since I had starved it for a day.

Now when this fly turns away from the camera, one can certainly see that its wing markings are very much like spider legs. Both males and females display their wings when encountering one another, but what would happen if I introduced a jumping spider?

So out to a local field I went, and soon returned with a test subject—a handsome male Phidippus clarus [see citation below]. What would happen if the two met? Would the fly react to the spider? Would the spider react to the fly (other than making a meal of it)?

In my arena I had the fly, feeding away, and the spider was kept several inches away under a clear plastic cup. When the spider was facing the fly, I would then lift the cup and make ready with the camera. After about 10 tries (I should have counted, but I didn’t), I could definitely say: I am not sure! Most times the spider did look at the fly, and sometimes it paused to look at it, as it was doing here for some seconds. But then it would turn and walk away. At no time did it stalk the fly, nor did it hustle off like it was fleeing. So I can’t “read” what the spider saw of the fly other than that it wasn’t prey.

Meanwhile, the fly just kept feeding, and it did not seem to react to the spider at all. But on one occasion – just one! – the fly certainly did seem to react to the spider by suddenly spinning around (it was facing away before), and it held out its wings. Here is that moment, with the fly out of focus in the background.

And here is a second picture, now focused on the fly. That is not a relaxed posture. The spider for its part just paused briefly, and then moved away.

I don’t know what to say about this informal experiment, other than that the one response from the fly encourages me to try it again. I am currently keeping an eye out for more of the flies.

As a kind of postscript, there is this lovely paper which proposes that many species of insects from several different orders may be mimicking jumping spiders to ward off predation. There are lots of cool and enticing pictures, and the readers here will certainly enjoy having a look.

Thank you for looking!

Readers’ wildlife photos

August 5, 2023 • 8:15 am

We’re down to two or three sets of photos, so things are getting dire. If you have good wildlife photos, send them in now (but not between the 11th and 21st, when I’ll be gone). Thanks.

Today Tony Eales, back from his African safari, now sends us photos of African bugs. His captions are indented, and you can enlarge his photos by clicking on them.

As I said in an earlier post, there were not many bugs, June being well into winter in southern Africa. There were, however, still bugs and creepy crawlies of different kinds. Here are a few of them. Unfortunately I don’t really know much about most of these species but I’m reaching out to various places to learn more.

Found this cool grasshopper nymph in Moremi Game Reserve:  Abisares viridipennis:

At the same camp I found this lantern fly, probably Druentia sp.:

I found this strange bark mantis in Chobe. It barely has the classic raptorial forelegs that are usual for mantises. Amorphoscelis sp.:

At the same camp we found this elongated assassin bug, Rhaphidosoma sp.:

This mantis, while more classically armed, was very weirdly adorned to help it blend into the background. Sibylla pretiosa Cryptic Mantis:

We saw the evidence of a very unusual moth that could really only live in an area with thousands of grazing mammals like southern Africa. Ceratophaga vastella, the Horn Moth. Unlike the majority of moth larvae, these feed on mammal horns rather than plants. [JAC: the marks on the horns are caused by larvae; as Tony explained, “You can see the worm-like tunnels On the surface of the horn and empty pupal cases sticking out of the horn”]:

Here’s one of the major shapers of the landscape, Macrotermes sp. I don’t know if the species I photographed here are the same ones that are responsible for the large mounds that we observed, especially in the Okavango, but they are in the same genus. These termites are unusual in they are fungus farmers rather than eating the plant material directly:

Some of the more impressive insects I encountered were hymenopterans. Here is a Slender Tree Ant in the Tetraponera natalensis species complex:

Stingless bees Meliponula bocandei, much larger than the Australian and Southeast Asian species I’ve encountered:

Paltothyreus tarsatus, the large African Stink Ant:

A large velvet ant, Stenomutilla sp.:

And of course, I found a wide variety of my favourite group, arachnids. Including my very first member of the Solifuges, or Sun Spiders. Apparently this family (Solpuginae) of Sun Spiders is called Common Romans. I’m not sure what that is about.

I also found an Orange-lesser Thicktailed Scorpion (Uroplectes planimanus):

And these spiders were absolutely everywhere after dark. I was confused as by size and habit they seemed so much like the huntsmans (Sparassids) that I know from home, that I assumed that’s what they were. But in fact they were what are known as Flatties or Wall Crab Spiders (Selenopidae). I should have noticed the different eye arrangement. This one is probably Selenops sp.:

But my favourite spider was this impressive Wandering Spider (Ctenidae). As yet, I have no ideas about the genus but I’m asking a few knowledgeable folk about it:

Readers’ wildlife photos

July 18, 2023 • 8:15 am

Regular Mark Sturtevant is back with a batch of lovely arthropod photos. Mark’s captions are indented, and you can enlarge his pictures by clicking on them.

Here are more pictures of arthropods. Some are from area parks, and others are from my house here in Michigan.

First up is an Antlion larva, Brachynemurus abdominalis. One can find the conical pits that these little beasties make all over what I call the Magic Field. How they use their pit to ensnare passing insects is shown in this video.  Although they are easily extracted with a spoon to be taken home for pictures, actually getting pictures was not that easy since they generally want to scuttle backwards in an attempt to bury themselves. Right now, I am keeping a few larvae in cups of sand and feeding them ants (which is always entertaining), with the aim of later photographing the pupal stage. Antlion pupae are interesting in that they are still ill-tempered and they bite:

I came upon this wasp-mimicking beetle (Necydalis mellita) along a woodland trail. That it is indeed a beetle is proven by its elytra, even though they are very short. I’ve seen these before but could never get a picture because they are alert and flighty (wasp mimics tend to be wasp mimics all the way). But this one allowed a few pictures. It belongs in the longhorn beetle family:

Next up is a Big Sand Tiger Beetle (Cicindela formosa). These lovely but very alert beetles are common around here in sandy areas. Some days, nothing will get you a picture of one, but on this rather cool and overcast day the task was pretty trivial. Tiger beetles used to be in their own family, but now they have been absorbed into the ground beetle family:

Another challenging beetle is shown next. This is a tumbling flower beetle, Mordella marginata. Tumbling flower beetles belong to their own rather obscure family, and they are normally found on flowers where they eat pollen. There, the least disturbance will cause them to live up to their name as they curl up and fall to the ground:

Next are two grasshoppers because I really like grasshoppers. The first is a ‘hopper nymph of uncertain identity, but it most resembles the Two-striped Grasshopper, Melanoplus bivittatus.

Following that is the Northern Green-striped Grasshopper, Chortophaga viridifasciata:

Over the previous summer, I made it a regular habit to scour the front porch in the morning to look for insects that were drawn in overnight by our porch light. Among the more common squatters were these very small Mayflies which I believe to be Callibaetus ferrugineus. First are two females. The close-up picture is focus-stacked with my super macro lens, as are all of the remaining pictures here. She looks pretty strange, as all Mayflies do, but get a load of the male in the next picture.

Here is a male. I still remember my astonishment seeing the first of these! The upward turret-shaped portion of their compound eyes are thought to be used to watch for females:

This set finishes with a couple spiders. First up is a Slender Crab Spider, Tibellus sp. These are shaped to stretch out along grass blades:

And finally, here is a Ground Crab Spider, Xysticus sp. The super macro lens lets me peer into a new world, but I wasn’t expecting that face to look back from it!:

Readers’ wildlife photos

July 14, 2023 • 8:15 am

Today sees the return of Robert Lang, physicist, origami master and, today, photographer.  Robert’s narration is indented, and you can click on the photos to enlarge them.

More local animals

The Los Angeles basin is a vast urban/suburban metropolis, but its natural boundaries of ocean and mountains are abrupt with sharp transitions created by water and steepness. The northern boundary is formed by the San Gabriel and San Bernardino Mountains (collectively, the Transverse Ranges) and they rise steeply from many back yards along the range. My studio is about 20 feet from the edge of the Angeles National Forest; this gives rise to many wildlife encounters, both at the studio and on the trails that climb up from the back property line. Most of these pictures are fairly recent.

One from last fall that I’ve been saving for RWP is this California Tarantula (Aphonopelma sp.). Probably a male, because he was out and about; in the fall, the males go on walkabout looking for females (who mostly stay hidden in their burrows):

Then we turn to a couple of reptiles. The Western Fence Lizard (Sceloporus occidentalis) is one of the most common lizards around; just walking down the front steps, I’m likely to see one (although it’s rare that they stay still enough to be photographed). They are highly variable in color, and the same lizard can appear either light or dark. In the morning, they are dark to absorb the sun’s rays; then in the afternoon, after they’ve warmed up, they lighten their skin and their lovely iridescence becomes visible:

I was pleased on a recent hike to see a Blainville’s Horned Lizard (Phrynosoma blainvillii) at an elevation of about 4000 feet. They used to be more common in the San Gabriels, but earlier in the previous century their numbers were reduced by collectors gathering them for the curio trade, and they’ve never fully come back. I really should have taken a wide-angle photo of this one; it would have been a great candidate for the “Spot the …” series, as it was so perfectly camouflaged against the sand and gravel I nearly stepped on it:

Another reptile that I’m glad I didn’t step on was this Southern Pacific Rattlesnake (Crotalus oreganus helleri), who was stretched out across the trail. He was pretty chill, though; didn’t budge as we approached, and so we gingerly stepped past. A nice set of rattles on that one!

We have three kinds of squirrels around; ground squirrels, gray squirrels, and the (introduced) Fox Squirrel (Sciurus niger). The local rattlers are happy to dine on any of them.

We also have both crows and ravens; crows are more common down in the neighborhoods, while ravens like this Common Raven (Corvus corax) dominate up in the chapparal. This one is perched on the top of one of last year’s blooms from the Whipple Yucca (Hesperoyucca whipplei):

Larger creatures sometimes come visit the meadow behind the studio. A not infrequent visitor is the coyote (Canis latrans). Although this one was (barely) within the National Forest, they come far down into the adjacent neighborhoods, where they find plentiful food in the form of dropped fruit, loose garbage, and the occasional domestic animal whose owners ill-advisedly allow them to roam free:

Another frequent large visitor is the California Mule Deer (Odocoileus hemionus californicus). This time of year, the bucks are in velvet, like this one. We had a very wet spring, so there is a lot of browse in the mountain canyons and not much to lure them into the meadow, but in the fall, when the acorn crop starts to fall, they’ll be visiting twice a day:

In much of California, the urban/wilderness interface usually exists in one of two states: (1) recovering from the last wildfire; (2) stocking up for the next wildfire. A year ago we had a relatively small wildfire just across the canyon; fortunately, it was a cool day with not much wind, and the fire crews held it to just a few acres:

I spent the afternoon watching the firefighters dragging hoses for hundreds of yards up the ridges while helicopters and fixed-wing aircraft dropped water and fire retardant. I am in awe of the firefighters, who were clambering up cliffs that I wouldn’t even try to scramble under the best of circumstances, while they were wearing and/or carrying 50 pounds of kit and dragging hoses. Within a few hours, they had things under control. The drifting smoke and red fire retardant gave things an almost surreal appearance as they were mopping up:

That was a year ago. One thing about the chaparral is it recovers quickly from fire (indeed, many plants rely on it), and after this spring’s wet rains, the formerly bare ground is covered in new growth, and the burned bushes have resprouted. They’re getting ready for the next fire, which is bound to happen sometime; it’s the nature of this bit of Nature.

Readers’ wildlife photos

June 16, 2023 • 8:15 am

Mark Sturtevant is back with another batch of spider and arthropod photos (“harvestmen” aren’t spiders). His captions and IDs are indented, and  you can click on the photos to enlarge them. Our photo tank is nearly empty, by the way. Sunday may be our last day!

Last summer was a good one for getting some especially nice buggy pictures, although work and being dragged to vacation in urban areas did reduce the volume of pictures that I could gather. But I did my best. This set is all about some early-season spiders.

There was a big marbled orbweaver (Araneus marmoreus) in the garden late in the previous season (you saw pictures of her), and she left an egg sac. So early this summer my wife reported that they had hatched, and here are the bebbies. They would disperse when disturbed, but after a time they would gather together again into a tight little ball of tiny spiders. I love all those little baby bums! 

Here are some focus stacked pictures of jumping spiders, taken with the manual Venus/Laowa 2.5-5X wonder-lens. Jumping spiders are of course very active, so high dozens to over a hundred of pictures were needed to get successful but short stacks. It also helped to use psychology on the subjects, as explained below. 

The first one is a tiny ant-mimicking jumping spider, Myrmarachne formica. Readers may remember a male of this species that I had recently shown which had over-sized chelicerae. The one here is a female. To get her to stay in one area, she was marooned on a leaf that was pinned out in a cup of water. Since she was unwilling to cross the moat, I could zero in on her much more easily. No subjects were harmed in taking these pictures, btw. 

And here is our charismatic bold jumping spider (that is its common name), Phidippus audax. It is useful to think of jumping spiders as being like cats, so here I fashioned a tiny cup out of a leaf and let her explore it. Being cat-like, she had to sit inside the cup, and she even sat still for almost a minute which is an eternity for such spiders! 

Here she is again, but now she’s pausing atop a foam rubber stopper while sizing up the distance between her and the lens (she attempted the leap several times). You can see that one of the front legs had been regenerated. 

Here is a close crop of the previous picture, and this show-cases the incredible quality of this super macro lens. Y’all should click again to embiggen this one! Many hours were needed to clean up most of the artifacts from the focus stack and from the Topaz Sharpen AI program that I’ve also started to use, but the result is a contender for my favorite critter picture. The eye reflections are the diffusers that were used on the twin flash. Those diffusers are now being re-built, as is required since that is one thing that must be regularly fussed over in this hobby.

 

Next up is an unknown species of wolf spider carrying her egg sac. I did not know that adult wolf spiders could be this small. 

And finally, this is a focus stacked picture of a female harvestman (likely Phallangium opillio). OK, it’s not a true spider, but just look at that weird little face! Male faces are even stranger, but they are super restless. I will do my best to get the picture this summer. 

Readers’ wildlife photos

June 15, 2023 • 8:15 am

A few contributions have been coming in, so we’re good through the weekend, I think. Today we have a new contributor, Małgosia Borkowska-Tarr—from Poland. I’ve also added two photos sent by reader Diana MacPherson from Canada.  If you can ID any of the photos, please do so in the comments.

Everyone’s ID and captions are indented, and you can enlarge the photos by clicking on them.

My name is Małgosia and I live in Łuków (eastern Poland) with my husband Brian. He is from California and thanks to him I found out about your website “Why evolution is true.”  I took some pictures of wild bees in our garden. There is Anthophora plumipes, Osmia biconis and some others.

From Diana, who found a spider mimicking an ant:

We still have cute spider ants. I took this picture with my 100mm macro lens just now. He’s so small and so convincing as an ant but here he is with his cute spider face.

And here’s a pseudoscorpion:

He’s very tiny – about 2 mm. I took this with a 100mm  macro lens so he looks a lot bigger. There are so many species I have no idea what the Latin binomial would be for this guy but he was near my window where I saw the small ant mimicking spiders. I think that window is host to a lot of smaller insects & such that these small arachnids can eat.

Readers’ wildlife photos

June 9, 2023 • 8:15 am

Mark Sturtevant has rescued us from a day with no wildlife photos (I have about four batches left and will have to do this only sporadically if I run out). PLEASE send in your good photos.

Mark’s IDs and notes are indented, and you can enlarge his photos by clicking on them.

Here are pictures from the previous summer. The pictures were taken generally in May, near where I live in eastern Michigan.

First up is a lettered sphinx, Deidamia inscriptum. The larvae will feed on wild grape and Virginia creeper:

European pine sawfly larvae, Neodiprion sertifer. These were accidentally introduced into the U.S. in the early 1900s, and they feed, en masse, on several species of pines. I regularly see them by the thousands in some areas. This group of early-season youngsters are in a defensive posture where they are ready to collectively spit toxic chemicals if necessary:

Next is a flower chafer beetle, Trichiotinus sp. I always find them on white flowers. Always:

I have been using my 2.5-5x Venus/Laowa super macro lens to try to get facial portraits of arthropods. The next picture is an early effort. This bizarre spider is a female long-jawed orb weaver, Tetragnathaelongata, and they are super common near water. People recreating on rivers and lakes may learn to hate them for their scary jaws and habit of dropping in on you from where they concentrate near shore. But they really are as benign as ladybugs, and their long jaws are used as forceps to delicately pluck small flying insects from their webs. Getting this manually focused stacked picture took a lot of work since these spiders can pretty much fly. By that I mean they will run away, clamber up high, and stand on their head to send away delicate silk draglines into the air currents. As soon as they get a tether on something across the room, they secure the near end and off they go – a flying Wallenda on a tightrope. I had to chase after this one dozens of times to return it to its perch, and so this picture required a determined sense of humor. Right now I am fixing to exhaust myself again with a male spider, simply because they have an even more gnarly face:

Late last summer I had collected several egg cases (oöthecae) of one of our largest insects, the Chinese mantis (Tenodera sinensis). The plan was to photograph them while hatching, as that is quite a sight. Over and over, the oöthecae would hatch in the pre-dawn hours and I would miss the whole thing. But one batch was slower and I managed to get something of it as shown in the next two pictures. The babies all wiggle out while wrapped in a tight membrane. They will later break free of that, and soon they are moving around:

And here is a youngster that is about the size of a mosquito posing on a tiny mushroom. I released all of them in a field near home:

Finally, here is a fuzzy bumble bee bum. It is a small internet meme to get pictures of bees deep in a flower, with their cute little butts sticking out, and here I finally got one! I am not sure about the species: