Rain Beetle

Found a bug
Location: Northern Ca foothills near Auburn CA
November 13, 2011 1:58 pm
Hi, I found this bug on my doorstep this morning. It is about 2 inches long. Not sure what kind it is and if I should be concerned about the trees or house. We live in a heavily wooded area, many pines and oaks in the Sierra Nevada foothills near Auburn CA.
Can you tell us what bug this is?
Signature: Duke

Rain Beetle

Hi Duke,
Congratulations on your wonderful sighting.  This is a male Rain Beetle in the family Pleocomidae (see BugGuide), a family with a range that is limited to the west coast of North America.  Rain Beetles are a very unusual family of beetles.  Larvae live underground and feed on the roots of oaks and conifers and they can remain underground for as long as ten years.  Mating activity is triggered by rain.  Only male Rain Beetles have wings, and they will circle the ground until they locate the burrows of a flightless female.  There are many species of Rain Beetles and many have very limited ranges.  An expert is required to distinguish one species from another.  There was an excellent article in the LA Times several years ago on the Rain Beetles. 

3 thoughts on “Rain Beetle”

  1. This is a unique specimen and does not represent anything described by locality , if your location information is correct . You have something new recorded for that area ! 1. We have over a dozen Unidentified Pleocoma in the central valley that need to be named and this is either one of these…….. or…. 2. something …. different . 3….only Pleocoma crinita or Pleocoma conjungens comes close in appearance with current described Species . So , it looks like I will have to spend some time looking for these ” Auburn ” specials . Let me know if you get any more for a Exact physical description . Very nice ! Gene St. Denis SNR

    • Hi Gene,
      What’s That Bug? is very grateful for all of the information you have provided over the years regarding Rain Beetles. We hope you will continue to update us to your findings.

  2. Folks , I now have some ideas about it being a male Pleocoma fimbriata ( northern sub group ) . With a head lam shoot I could pin it down . Cheers ! Geno


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