We have another batch of lovely arthropod photos from reader Mark Sturtevant:
We begin with two species of deer flies, which I am sure are viewed not very fondly by most readers. They can be rather beautiful, however, and it is only the females that are blood suckers. The first looks like Chrysops moechus, and the second seems to be in the Chrysops flavidus group of species. This one had sunk its proboscis deep into my thumb but I felt absolutely nothing.
During the summer the family took a vacation to San Francisco. Although it was of course too cold for a reliable abundance of insects, I could at times escape the usual tourism to explore the spectacular gardens in and around Golden Gate Park. There is a famous and ancient botanical garden just outside the park that had a butterfly house which held many native species. Two of special interest to me included the lovely buckeye butterfly (Junonia coenia), and the picture after that is of a mourning cloak butterfly (Nymphalis antiopa). I was especially glad to see the mourning cloak since that is a species I had never photographed. Although very long-lived, they prefer wooded areas and there they only spend brief periods in flight. Through most of the summer they estivate and when they do actively forage for food they prefer to feed on tree sap and not flowers.
Within the Golden Gate Park there are extensive nature trails, and in one region host plants are maintained expressly to provide a habitat for pipevine swallowtails (Battus philenor). Pipevines!! I love those butterflies, especially the males which have iridescent blue hind wings as shown here. The local subspecies in the San Francisco area had been severely threatened by development, and so there is a significant grass-root effort to cultivate their host plant to help recover the population. You have to love the San Franciscans! I saw an adult female flying around, but she would not sit for me. But there were many larvae on the pipevines in the park, and the next pictures shows one. Their coloration is a warning that they are toxic to predators. The pipevine chrysalis in the next picture was one of many on a building nearby.
Last Winter I was visited by a student who wanted to show me cellphone pictures of a spider that she had found at a nearby lake. I about fell out of my chair since what she had were pictures of a six-spotted fishing spider! This species (Dolomedes triton) is a large spider that is a close relative to our huge nursery web spider (D. tenebrosus). D. triton is slightly smaller in leg span, but is more robust in build.
Six-spotted fishing spiders are basically aquatic, and are typically found sitting on floating vegetation out on the water or lurking along the the waters’ edge. They are powerful hunters that can lunge into water to take small fish, and they will also go underwater to hide. When submerged, they are kept effectively dry by a dense pile of fine hairs that traps air around their body. I had no idea that this species was around here, and once the weather warmed up again I definitely was on the lookout for this lovely spider. I found them soon enough, as shown in the final pictures.
The first of these pictures shows one sitting out on a lily pad. When I dragged the lily pad closer to shore for pictures she quickly dove into the water. I carefully started to turn the lily pad over and she immediately popped back out, so she was probably just clinging to the underside of the lily pad. Their behavior does not seem that different from nursery web spiders in that they are strongly thigmotactic, meaning they really want to have something under their feet. It is a bit of a relief that these large and fast spiders are not inclined to jump!
The last picture is one of my favorite pictures from last summer. At a pond I found a big female fishing spider eating a dragonfly (I think it was a blue dasher dragonfly), but she was sitting on a piece of styrofoam in the pond. So I used one of the poles that I carry to drag the trash to a patch of lily pads, and then I pushed the Styrofoam under water. It was a great fortune that she immediately scrambled over to the lily pads, hauling her meal under her body like a leopard with an impala. I could then move the lily pad close to shore for pictures. For this one I was lying flat on my stomach in the very squelchy and fetid mud. After all that I was a very messy but very happy boy. If possible, I recommend trying to enlarge the picture by double-clicking on it to better appreciate the fine pile of hairs that provides an effective waterproofing system for these amazing spiders.