Tuesday, January 24, 2012

Pleocoma tularensis

Well it finally happened. After three years of searching, I finally found a rain beetle. I’m guessing that it is Pleocoma tularensis, but with the superficial (shall we say “stormy”) nature of rain beetle taxonomy, it might end up being P. fimbriata. In A.C. Davis’s revision, the two species are very difficult to distinguish. Linsley’s key to species resorts to geography to tell them apart. To complicate things, I found this individual in Fresno County fairly close to the point where the distributions of the two species meet. When this group is better understood, I expect that P. tularensis will be a subspecies of P. fimbriata (as Davis originally proposed). For those of you new to rain beetles, they are fairly large scarab-like beetles (family Pleocomidae at the moment). This one is well over an inch (30 mm) long.

Rain has come quite late this season. We normally have a good storm in November (maybe earlier). And it is this first storm that brings out the beetles (at least in many of the species). The first storm this season came this last weekend (in the middle of January). It starting on Friday afternoon and so I hurried home from work the same day, grabbed a bite to eat and drove up to Bretz Mill Campground about an hour above Fresno. I chose the place because the area combines grassy areas with mixed forest and riparian habitats. And it is also between 3,000 and 4,000 feet – a good elevation for rain beetles.

I put up two lights in the rain and waited a couple of hours without success. Maybe I should have left the lights on longer. Not wanting the rain to ruin my lights, I put them away and crawled into the back of the truck to sleep. By 6:00 the next morning I was wide awake and decided to drive home. Fortunately, I passed by a small community along the way with lights on and stopped to see what I might find. I found this individual crawling along the ground below one of the lights. (Both pictures are staged.) It was 6:40 AM, not much above freezing, with small patches of snow about, and with not another insect in sight. What a great way to catch beetles – and such an impressive one at that.

Saturday, January 21, 2012

Rhagium inquisitor

The ribbed pine borer Rhagium inquisitor (Linnaeus) is a longhorn beetle that occurs around the world in the Northern Hemisphere. The larvae usually live a couple of years under the bark of dead pines. After pupating in the summer, adults emerge in the fall and overwinter inside a frass wall beneath the bark.

These appropriately named beetles have interested insect physiologists for a number of years because of their ability to withstand harsh sub-zero winters above ground (albeit somehat protected inder an inch of bark). They have a combination of anti-freeze compounds in their blood that enables them to avoid ice crystal formation at temperatures below -16 degrees C. Here are a couple of the frass wall hybernacula that I found last week near Watsonville, California.

We were visiting the beach and I found a couple of the beetles on a dead Monterey pine (Pinus radiata) just a mile or so from the coast. It can be seen in the habitat shot off to the right.

Monday, January 9, 2012

The Middle Fork of the Tule River

The Middle Fork of the Tule River runs through Wishon Campground east of Porterville, California. It is a nice place to enjoy the Sierras in the winter. The campground’s elevation is just under 4,000 feet, which means that winter campers will often wake up with frost on the ground (as we did last month) although it will quickly disappear. The forest is quite diverse with valley (Quercus lobata) and canyon (Q. chrysolepis) oaks intermixed with California incense cedar (Calocedrus decurrens), white fir (Abies concolor) and ponderosa pine (Pinus ponderosa). There are also giant sequoias (Sequoiadendron giganteum) just up the trail in Mountain Home State Forest. The giant tree next to Spencer is the largest canyon oak I’ve ever seen. It’s near the bank of the Middle Fork of the Tule River maybe a mile above Wishon campground (you’ll come to a fork in the trail and will want to take the lower path leading down to the river). There’s a large hole at the base big enough for a grown man to sleep in and cook dinner on a stove.

But what surprised me most on our hike (along the trail just north of the campground) was the small groves of California nutmeg (Torreya californica) that grow like inconspicuous understory shrubs. In fact, at first, I passed several and wondered at their large flat needles, trying to figure out what sort of fir it could be. I didn’t realize that California nutmegs occurred so far south. As I was to learn later, this is probably the southern-most distribution of the species. Although I bet a few may creep over into Kern County if somebody were to make an effort to find them there.

This last picture is of a waterfall along the trail maybe two miles above the campground. It’s a nice place to relax and there’s a great swimming hole just below. I think I’ll be coming back for a swim when it’s warmer.