Diptera.info

Posted by Nosferatumyia on 30-07-2008 19:08

This is a female of the yellow berberis fly Rhagoletis meigenii Loew. Seventh tergite and sternite, like in all the higher tephritoids, are fused forming the oviscape, or the ovipositor sheath (the black tube on the picture). 8-9th segments and the cerci are fused forming the aculeus, a piercing part of the ovipositor. You see its apex exposed from the oviscape. These flies often pierce fruits to feed with their juice or mark the fruits they have layed eggs in, with kairomones to prevent oviposition by other females.

Posted by JariF on 30-07-2008 19:23

Thank You Valery so much for this interesting explanation :) Only one small detail I must ask to be sure. So far meigenii is not in our list of species, but alternata and cerasi are. Maybe this is female of one of them ?

Jari

Posted by Kahis on 30-07-2008 20:48

Hmm, the wing pattern does indeed look like meigenii! Jari: does the host plant (Berberis - happomarja in finnish) grow where you caught this fly?

Just as a sanity check: are we sure it isn't a Trypeta/Vidalia/Stemonocera/Cornutrypeta?

Edited by Kahis on 30-07-2008 20:55

Posted by JariF on 30-07-2008 21:00

The fly is from my garden. I have never tried to use malaise in here but after two days I have as many flies I normally get in a week. Yes, there are indeed several bushes of Berberis nearby. Even in our garden :) You will see the species after two weeks when I come home.

Jari

Posted by Nosferatumyia on 30-07-2008 21:12

The only other species, which looks similar, is Trypeta immaculata Mcq. The ovipositor on the photo and the head shape look more like in R. meigenii rather than in a Trypeta. Nevertheless, to my knowledge, R. meigenii has not been ever recorded from Finland, but occurs, for instance, in the north of Estonia.

I am curious to see more pictures of its head in profile or more specimens, because it could be the first record for Finnish fauna, and I'd prefer to exclude any possibility of T. immaculata misidentification.

It is not new that the flies are found in ones own garden.

Andy Whittington, for instance, recently found a well-established population of the artichoke fly Terellia fuscicornis Lw. (of mediterranean origin) in the garden of the house he bought in Scotland; it was alsi new for the UK.

Edited by Nosferatumyia on 30-07-2008 21:18

Posted by Nosferatumyia on 30-07-2008 21:21

Jari, try to observe them directly on the bush - the flies walk around on leaves and fruits in the sun spots. Or try to sweep with the net (must be a strong one! the shrub is spiny)

Posted by JariF on 30-07-2008 22:02

I couldn't wait. Here is another angle with better view of the wing pattern and the shape of antenna. In fact it really looks a lot like the meigenii in Merz book.

Jari

Posted by Nosferatumyia on 31-07-2008 08:18

#10

Jari, I have re-examined quite large series of both R. meigenii and Trypeta immaculata. Ofthe external characters, alongwith the wing pattern, frontal setae are like in R. meigenii (directed medially and slightly posteriorly in Trypeta immacilata). Both species differ from each other with certainty from the aculeus (needs dissection): lateroapical margins serrate in Trypeta, but smooth in Rhagoletis.