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Monday, August 8, 2016

Some July Arthropod-oriented Miscellania

Dr. Art Evans paid a visit for a couple days, and we spent some time in the field, primarily looking for species of value for his upcoming western beetle book.

One the first night at my patio black light, one of those rarely seen prionids, Tragosoma pilosicorne made an appearance. This is only the second individual of this species that I have seen here.

Tragosoma pilosicorne
On the way back from a drive out to the In-Ko-Pah area on the border of San Diego and Imperial Counties, we checked out Boulder Creek Road near McCoy Ranch Road and found several Onitis alexis under cow patties. Never a common dung beetle in my experience in San Diego County, but I have observed it in quite a variety of locations now: Rancho Bernardo, Lake Sutherland, Ramona, Lake Henshaw and now in this latest locale.

Onitis alexis. One of several dug from burrows under the cow dung. An introduced species originally from southern Europe and Africa, deliberately released in California to control cow dung accumulation. Specimen collected by A. Evans.
This small orb weaver was spotted after dark on my property as we looked for nocturnal species.
Body length around 10 mm (so small).
On the second day we explored the San Felipe Creek area. Quite a few hymenopterans and dipterans were out at the Eriogonum blooming near the creek in one spot. Macrosiagon sp. (likely M. cruenta) were present in the blooms also. This family of beetles lay eggs in flowers which hatch into small larvae. The larvae then hitch a ride to the nest of bees or wasps that visit the flowers. Then the beetle larvae parasitize the early larval stages of the hymenopterans.


Macrosiagon sp. (likely Macrosiagon cruenta). Specimen collected by A. Evans.
On the way out of the desert a dead deer presented itself along the road. Art stopped to look for dermestids and histerids, and was rewarded for his efforts. Why let a little smell deter one from the possibility of interesting beetles!



6 comments:

  1. That area between Scissors Crossing, to San Felipe, to Ranchita is notorious for deer collisions. So is the stretch of Hey 79 between Warner Springs and Sunshine Summit.

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    1. This was the first I've seen (but I'm not out there that frequently...). The riparian area is very rich along there.

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  2. The Tragosoma pilosicorne, I think that's the same beetle that was launching itself at my windows for awhile. Back in July or August I was on the front deck at night and as I went to go inside I half-crunched one of these guys. He was okay, and then for the next several weeks if I left a light on in the living room I would hear them loudly hit the window every 10 minutes or so until I turned the light off. Thought it was a palo verde beetle, but this looks more like what I saw (not jet black like the palo verdes)

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  3. The Tragosoma pilosicorne, I think that's the same beetle that was launching itself at my windows for awhile. Back in July or August I was on the front deck at night and as I went to go inside I half-crunched one of these guys. He was okay, and then for the next several weeks if I left a light on in the living room I would hear them loudly hit the window every 10 minutes or so until I turned the light off. Thought it was a palo verde beetle, but this looks more like what I saw (not jet black like the palo verdes)

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    1. Actually Tragosoma seem "rare" hereabouts (at least in my experience). Prionus californicus is the really common species - and yes, they will bang into screens/windows for hours. They are usually an inch or more in length...

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