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We've been seeing a lot of bee flies in the genus Geron in our yard lately (link is to previous post).

Geron bee flies are more slender than most of their relatives and have a "humpbacked" appearance because their thorax bulges up in the back (dorsal surface).

 

As stated at BugGuide, the adults use their long, prominent proboscis to drink nectar from flowers. They seem to prefer sunflowers.

Because of their fuzzy bodies, they pick up pollen while feeding on nectar. When they carry the pollen to another flower, they help pollinate it.

So why were there so many of these flies on the palo verde tree this morning?

Looking closely, I noticed some caterpillars. Bee flies are parasites of other insects in general. Geron bee flies are parasites of caterpillars. These adults were probably looking for a caterpillar to lay their eggs on.

I'm going to spend some time watching the caterpillars to see if I can find out more. Look for an upcoming post about them.

Until then, do you have Geron bee flies in your yard? What flowers are they visiting?

The little leaf cordia (Cordia parvifolia) is covered with white blooms right now.

They attract quite a few flying insects.

Wonder why this fly is sitting on a leaf rather than a flower.

Most of the leaves are dry and slightly fuzzy.

However, some of the leaves are dripping with nectar, which seems to be coming out of glands near the petiole.

Flies have a mouth like a sponge which they use to sop up liquids like nectar.

The little leaf cordia is a visual treat for humans and a sweet treat for insects.