Diptera attracted by solvents!!

[IanF]

These small Diptera were strongly attracted to a white spirit based wood stain being used on window frames. About a dozen specimens arrived and were attempting to feed on the fresh surface, accompanied by much "wing waving" behaviour. Any identification suggestions gratefully received. One image shows wing venation, the other shows head detail - apologies for the poor images,

Ian F.

[Jason Green]

Afternoon Ian,

It's a Tephritid fly, Anomoia permunda. The wing-waving is the male's courtship-routine - I assumed some girls were in the group.

Take care,

Jason

[IanF]

Many thanks Jason. I believe that all of the specimens I observed were "wing-waving" and all looked identical (not sure if males and females are visibly distinguishable?). It leads me to speculate whether the solvents in the woodstain may have been acting as some kind of pheromone? I've also noticed these flies congregating around a piece of cloth with white spirit on it - again all "wing-waving". Any thoughts on this?

IanF

[IanF]

I have just found the following from New Scientist which may be of interest:-

The following answer has been selected and edited by New Scientist staff

The distinctive wing pattern and green eyes makes these flies easy to identify. They are a fruit fly of the family Tephritidae and the species is Anomoia permunda. The larvae of these flies feed on hawthorn berries.

Insect behaviour is predominantly governed by odour. For example, a female of a species will emit a pheromone to attract a mate. The male reassures the female that he is a true suitor, and not a predator, by emitting another pheromone when he is in close proximity. These chemicals are often common to many insect species, therefore different species will use a mix of chemicals, or confine their activity to different times of the day or year. That way they can use the same pheromone without fear of confusion.

When the female flies of Anomoia permunda search for suitable berries on which to lay their eggs, they do not look at leaf morphology, shape or colour. Instead, they follow a trail of odour, emitted by the hawthorn fruit, to find a suitable egg-laying location. If both fly and host derive a benefit from this odour, as is often the case, the chemical involved is termed an allomone. If only the insect derives a benefit, as seems to be the case with this fly, we call the chemical given off a kairomone.

So why are these flies attracted to white spirit? It is likely that the volatiles given off by white spirit are sufficiently similar to the pheromones emitted by hawthorn berries to fool the flies into landing there. Or perhaps the white spirit volatiles contain components of the pheromones the flies use to find a mate. Either way, the white spirit is luring them in under false pretences.

Terence Hollingworth, Blagnac, France

[Jason Green]

It's possible - I can't think why else, personally.

Males and females should be distinguishable with a view of the rear-end - girls back-ends should almost appear cone-like and blunt, often black and obviously used to lay eggs. The males' posteriors should be body-coloured with no obvious apendage.

[Miss Caretaker]

On a similar vein, whilst re-sealing the parquet school hall floor today with a very pungent sealant (Bourne Seal) I had to spent a lot of time peeling Episyrphus balteatus from the drying seal! I lost count of how many so I wonder if it is a similar reason to your Anomoia permunda...
Jo

[IanF]

It seems to me that these responses demonstrate how easily humans can disrupt the behaviour and life cycles of other organisms, often with very little being recorded (no dead bodies for example, as would be observed in mass mortalities). On the positive side it would seem that these responses could form the basis for survey and sampling methods, and also form the basis for some interesting research - perhaps this is going on somewhere already?

IanF