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Wednesday, October 9, 2013

Triggered by rain (or snow!)


I'm at a meeting in southern California this week, near Idyllwild which is close to 6,000 feet elevation.  It rained for most of the day and then started snowing around 5 p.m.  The photo above and the one below were taken looking up into the night sky.


Earlier in the day, when it started to rain, one of my colleagues found a very interesting beetle and kindly shared it with the rest of the group (Thanks, Paul!).  Upon seeing it, other people mentioned they had just encountered similar-looking beetles flying by.


These beetles are commonly known as "rain beetles" because they emerge with the first fall rain or snow.  They're in the genus Pleocoma.

They look a lot like June Beetles, but note the enlarged and spiny or rake-like front legs; the forked "horn" on the front of the head; the long and dense hairs on the underside; and how the antennal clubs are divided into distinct segments.  All of these features are visible in the next two pictures.  (And keep in mind that it's not June!)


These beetles have a fascinating life history.  The larvae live below ground for a long time up to 13 years!  They emerge as adults for a brief time only when the conditions are right (the adults don't feed).  The males fly around searching for females, but the females are flightless and are waiting for the males in burrows (hence the broad antennae of the males for detecting the scent of a female and the mole-like front legs for digging).

There's a lot more about these beetles that kept me saying, "Wow!"  You can read more about them here.

1 comment:

Claudia said...

Jackie, I had 2 "wows" while reading the additional information on rain beetles:

Wow #1: The known modern distribution of these apparently ancient beetles is restricted by the flightless females and is more or less correlated to areas of land that have never been subjected to glaciation or inundation by inland seas during the last two or three million years

Wow #2: On average, males of some rain beetles have only enough energy stored as fat to give them about two hours of air time.

Wow. Rain beetles!