I have a flying insects that look like greyish green bees. What are they?

Question

They drill holes in my sandy garden area. What the heck are they and why are they drilling holes? I live in central/southern CA.

Answer 1

Learn to ID them with the help of these sites -

http://bugguide.net/node/view/15740

http://greennature.com/article1899.html

http://www.einsteins-emporium.com/life/a...

http://www.whatsthatbug.com/

http://www.insectimages.org/

Answer 2

I dont know!!!