June 25, 2012
Location:  Mt Washington, Los Angeles, CA
We are indulging ourselves because we took some photos of insects while gardening over the weekend and on Monday, and though we have numerous letters provided by readers needing identifications, we decided to post some of our own sightings.

Mating Walnut Husk Flies

These Fruit Flies were putting on quite a show on the unripe peaches, and we suspected they might be up to no good.  The three individuals in this series of photos were getting busy and they seemed oblivious to the camera.  It appears that two males are vying for the females attention, and they formed quite a huddle for several minutes until their frenzied activity caused them to fall to the ground.  There were at least five individuals in the immediate vicinity of the six or so peaches on our very young tree, but the main mating activity was confined to the three individuals in the photos.  Upon doing the research today, we learned that these are Walnut Husk Flies, Rhagoletis completa, a species native to the eastern parts of North America that has become established in California.  According to BugGuide, they feed upon:  “Walnut husks primarily. It can attack other plants, such as peaches” and it “Damages walnuts, serious pest of walnut orchards.”  In Mt Washington, one of our local endangered treasures is the California Black Walnut, Juglans californica, which is endangered due to habitat loss caused by development in the hillsides as well as a new threat, the 1000 Cankers Disease.  We can’t help but to wonder if the Walnut Husk Fly might pose a new threat to the survival of the California Black Walnut.  We are postdating this entry to go live during the few days we will be out of the office.

Mating Walnut Husk Flies

Location: California

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