Saturday, April 11, 2009

King's River

This is the best time of the year to visit the foothills of the western Sierra Nevada. Lupines – colored lavender, white, blue, and violet – are covering the hillsides. The grass is actually green and the new oak leaves are small and shiny. Most of the trees have leafed out already or are bursting their buds. Scattered amid the sea of green are a few exceptions clustered in pockets of brilliant magenta. These are the flowers of the western redbud that hold back their leaves until the flowers have had their several days of glory.

We decided to spend a couple of days over Spring Break on the King’s River in the foothills of southern Fresno County, just north of King’s Canyon National Park. We camped at Kirch Flat just upriver from Pine Flat Reservoir.

King’s River is a swift yet fairly flat river. Its banks are sandy and lined with cobbles that have long endured the grinding pressure of the white-water current. There are California sycamores and lupines as big as sagebrush along the shore. A little further upriver the hillsides are covered with California poppies and a host of other wildflowers.

We found a large population of blister beetles (of the genus Lytta) feeding on the poppy petals. They were about half an inch long and were brightly metallic. Some individuals were coppery green while others were blue or just plain green. The young larvae of these beetles (called triungulins) are highly active and are known to jump from flowers onto solitary bees that come to feed. After hitching a ride to their nests, the immature beetles feed on the developing larval bees and grow fat in their underground nests. Once the bee larvae are consumed, the beetle parasitoids pupate in the soil and emerge as adult blister beetles ready for a new generation.

But this doesn’t explain the penchant that these particular beetles have for poppy flowers. It is more than likely that they are acquiring alkaloids or glycosides (both known to occur in California poppies) to protect themselves from predators. They certainly do like the flowers. We found several of them nearly skeletonized, while hanging behind the beetles, like drag lines, were strings of scarlet frass.

We also found a few scorpion flies (Bittacus chlorostigma, also known as the green stigma hangingfly) in the tall grass of the cooler shaded areas. They are similar to the crane flies that are numerous right now and, as a result, we almost overlooked them. One mating pair, however, was oblivious to our presence and let us get close enough to see their pointed mouthparts. They were locked in copula and a plant bug was clasped in their tarsi – apparently a nuptial gift for the female. The delicate yellow patch at the end of the wings matched their yellow legs and is the diagnostic character of this beautiful insect.

But perhaps our most interesting finds were near the river under driftwood. We came across a darkling beetle just under an inch long looking very much like an iron-clad beetle. These beetles are known to be very hard to smash (one has to wonder who first figured this interesting fact out). Their hard exoskeleton can sometimes be stepped-on without breaking. The insect we found was not actually one of these but a related species, Nyctoporis carinata. It is a dull blackish gray and has an intricate sculptured pattern on its back with ridges and grooves that even extend on to its head. It looks a bit like a small tank. Even its antennae look reinforced and armored.

Another interesting beetle under the driftwood was a snail-eating ground beetle (of the genus Scaphinotus, sensu lato). These remarkable insects have elongated mouthparts that they use to eat snails. The wing covers of this particular species were nearly round.

I should mention another curious incident that happened during our trip. Our campsite was spotted with the mounds of the valley pocket gopher (Thomomys bottae). There were piles of moist soil from their recently excavated tunnels and piles of drier soil from older ones. We didn’t think much of them until our dog (a poodle terrier mix) found one outside its tunnel just before sunset. The dog had probably never seen so many wild things in its life before (we were caring for it for a friend who, we expect, had not taken it out much) and so was a bit unsure of itself at times. The gopher, finding itself cornered by the dog, tried to dig a tunnel as fast as it could. Unfortunately it wasn’t fast enough and was forced to confront the small dog (looming as a giant to the poor rodent). It backed into its partially dug hole, confronted the dog and bared its re-curved teeth. If it made a sound I couldn’t hear it. Instead it tried to look as intimidating as it could. I was surprised at how long it managed to bluff the much bigger animal. It wasn’t until it tried to run for cover that the dog quickly grabbed it and then, just as quickly, drop it again. It didn’t have the nerve to finish it off. The gopher, however, had lost the use of one of its front paws and was otherwise unable to move. The dog, deciding either that the furry creature didn’t taste good or that it wasn’t worth the trouble, left the small creature to fend for itself. Knowing that it didn’t have much chance on its own, I put the poor creature out of its misery.

Overhead, the acorn woodpeckers were busy chasing each other from tree to tree and hardly noticed. A pair of kingbirds was perched on a bare branch near the river with their backs to us. They couldn’t have cared less at what we were doing. They were just gloating over the finches that they had scared away – and, no doubt, enjoying the sounding riffles of the river.

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