Anyway, the beetle is two inches long. The last pair of legs are 1 1/2 inches long, ending in two small hooks. The thorax on the underside is covered in a light brownish velvet. The elytra are (together) longish and shield shaped ( 1 1/4 inch by about 3/4 inch). the top of the thorax, just under the head is spined on the sides with two prominent spines and a smaller one towards the elytra. The antennae are jointed and about an inch long. it has two noticeable mandibles, which are an eighth of an inch long themselves (and curved). The overall color is a dark reddish brown, with the abdomen a more orangeish brown color. It also makes a kind of squeaking sound when disturbed.
I know, it would help to see it up close, but hopefully the images can help identify it. It has your basic beetle body plan, but it’s such a big thing, i’ve rarely seen this one around.
jeffro: Neither, exactly. Regardless of what species ( or genus ) it actually is, prionine Cerambycids are pretty neutral as regards gardens. Overall they’re bad beetles, I guess, because they do damage to trees ( mostly conifers ). But they should neither hurt, nor help, a garden particularly ( unless you have a pine growing back there ).
Slight correction - Prionus californicus is principally a root borer of deciduous trees ( they are reported as causing damage to oaks, madrone, cottonwood, and some fruit trees ). They will burrow into moist, dead, conifers, causing some loss to salvage operations ( something it has in common with Ergates spiculatus ).
Yes! It MUST be a Prionus! The image link Tamerlane gave looks JUST like it (especially with the elytra being a little shorter than the abdomen). It must also be a female…the antennae arent as saw toothed on the one I caught.
Also, I let the Prionus go back into my yard. I never found these insects until I planted some shrubs, a flowering plum, and added wood chips for mulch. I guess they like the conditions in the yard (i found a prionus there last year as well…and about the same time too).
Thanks sooooo much guys. I have been wondering what those beetles were for at least 12 years or so when I saw my first one (which freaked me out, the way it made noise when disturbed).