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    The Big Oak Flat Road between Crane Flat and the El Portal Road is temporarily closed. There is no access to Yosemite Valley via the Big Oak Flat Road or Highway 120. Tioga Road is open and accessible via Big Oak Flat and Tioga Pass Entrances. More »

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Rain Beetles

December 01, 2012 Posted by: EW - Park Ranger

Rain Beetles
Pleocoma sp.

It's December, and a light rain pitter patters on my roof. I get up early-4am. I love this time of morning, it's quiet, I drink a cup of joe, read, and ready myself for the day. Thud… thud... thud.  The "thud" breaking the early-morning silence is a male rain beetle flying into my living room window pane, lured, just like moths, to the lights. Unfortunately the flight of the rain beetle is not as glamorous as the flight of the bumblebee-but the journey, their life history, and their ultimate goal is truly epic.

After spending 13 years gnawing tree roots underground, the grubs metamorphose into adults whose sole purpose is to find a mate. The beetles are so focused on this mission they don't even break for a bite to eat (which is fine since they aren't endowed with functional mouth parts). The fat stored over the past 13 years is converted into two hours worth of flight time. Fall/winter rains trigger this nuptial flight in males and tunneling behavior in the flightless females. With specialized antenna flared out like giant moose antlers, the males hope to smell the females near their burrows (humans have the capacity to smell these pheromones, which have been described as lemon scented).Once the females have been found, the males then battle for mating rites. The prize for the winner is an opportunity to pass his genes on to the next generation. The celebration is brief, most males die shortly after mating or exhausting their fuel. Females live for a couple more months, tunneling 10 feet below the ground to lay their eggs, before they expire. These beetles have literally been waiting their entire lives for this moment, this one moment…to make new life and as one life flame is extinguished another is ignited.

rain beetle

Nature Scene, EW

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Did You Know?

Rockfall area and talus slope at base of Three Brothers in Yosemite Valley.

In March 1987, the largest historical rockfall in Yosemite National Park deposited an estimated 1.5 million tons of debris at the base of Three Brothers, closing Northside Drive for several months.