But a few Desert Marigolds (Baileya multiradiata) escaped the gardeners' scrutiny and keep reseeding themselves in little patches around Old Main. Yesterday on my way to lunch, I was looking there for bees to photograph.
While zooming in on some nectaring Leaf-cutter Bee, I noticed another insect that resembled the bees in shape and size, but was hovering and bobbing up and down nearly in the fashion of a bee-fly.
|Ripiphorus vierecki female|
I caught the beetle and took it back to the department, where the entomologists were dutifully impressed, but everybody else said 'yes, I see those all the time'. Hmm.
I did see a couple more Ripiphorus on my second attempt to get lunch, so I went on a diet for the day, and then I found another three on my way home on a patch of Desert Marigold on the west side of the Tucson Mountains. All were clinging to unopened buds. I looked again the next day, but all the flowers were blooming by then and there were no beetles, just bees.
There is a good reason for this. All the beetles I saw were females, ready to lay their eggs. I the picture above the ovipositor is visible under the beetle. She is going to plunge it into the unopened Marigold bud and deposit her eggs just in time for the larvae to hatch when the composite flower opens. At this time bees will visit the fresh flowers, and the beetle larvae will hitch a ride to the bee's nest where they will live first as internal, later as external parasites of the bee larvae (Nomia, Diadesia and other spp.)
|Male R. vierecki, Photo Greg Corman, Tucson|
Literature: The Rhipiphoridae of California (Coleptera)
By E.G. Linsley & J.W. MacSwain
Bull. Calif. Insect Surv. 1(3): 79-88, 1951