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ID for a tiny wasp? - Orasema occidentalis

ID for a tiny wasp? - Orasema occidentalis
Claremont, Los Angeles County, California, USA
May 30, 2011
Size: 1.5 - 2 mm
A couple of these tiny wasps were seen on Wedge-Leaf Honeydew, Horkelia cuneata ssp. puberula, at the Claremont Colleges' Robert J. Bernard Biological Field Station. As mentioned in a previous post, we are very interested in finding out about potential pollinators for this plant. Looking through BugGuide images, I wondered if it might be family Eulophidae, but I could be way off base. We will be most appreciative of any information about its identity!

Images of this individual: tag all
ID for a tiny wasp? - Orasema occidentalis ID for a tiny wasp? - Orasema occidentalis ID for a tiny wasp? - Orasema occidentalis

Moved from Eucharitidae.

Orasema occidentalis Ashmead, 1892
Hymenoptera: Eucharitidae. These are all ant parasites and in this case lay their eggs into the flower buds. Presumably the larvae latch onto thrips and then get carried into the ant nest (probably Pheidole) with the thrips prey. There they attack the ant larva and then develop on the ant pupa.

Thanks so much!
Thanks so much, Dr. Heraty (and Dr. Darling and =v=)! It's fabulous to have a specific ID and to get so much information about this wasp's biology as well as adding a new species to BugGuide. I will add it to our field station invert list.

This reminds me, however, that in our recent insect documentation efforts, we have so far avoided dealing with the ants, so I need to pay some attention to them. We have not thus far documented Pheidole at the field station, but that doesn't mean it's not there.

thanks much!

Eucharitidae --det. D.C. Darling
Dr Darling has forwarded the link to John Heraty who "should be able to provide you with an id."

Moved from Perilampidae.


You can see the deep parapsidal sutures, a bulging thorax, and small triangular-shaped abdomen in these images. Often found on flowers, they are mainly hyperparasitoids of lepidopterous larvae.

See reference here.

Thanks so much! So it likely is a hyperparasitoid, but not the family I had guessed. There are more kinds of these than I realized! What fascinating biology! This little wasp is both new addition to our list of insects on H. cuneata spp. puberula and a new family for our field station invert list.

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