How to Collect

Drosophila americana can be collected along the margins of marshes, lakes, and rivers.

I collect flies by placing buckets near the water.

  The buckets are baited with a mixture of bakers´s yeast and smelly beer (Guiness Special Export, for instance). Every 15-20 minutes they are visited and covered with a nylon menbrane that has a small hole in the centre. Flies are sucked from the buckets with the help of a canule.

I have been unable to collect flies when temperatures are above 25º C. Therefore, in most places, flies can be collected early in the morning or late afternoon, only. Bryant McAllister reports that flies can be collected in habitats with a high density of sandbar (Salix exigua, = S. interior) or black (S. nigra) willow only (http://www.biology.uiowa.edu/mcallister/bfm_flies.html). For S. nigra, the distribution, by county, along the USA is shown below (compiled using the information at Plants Database; green means presence; yellow means presence but that no information at the county level is available).

 

If it is your first time collecting flies, it is best to collect flies near a place where they have been collected before. Bryant McAllister created a very nice D. americana collection map that looks like this (collection map; blue means many flies; yellow means few flies; red means no flies):

Indeed, there seems to be a very good overlap between the S. nigra distribution and the places where flies can be collected.

D. americana flies look like this (20 days old male):

but I recomend a molecular identification using your favorite PCR primer pair. I recomend FuF and Fu523, that in my hands, always work. The region amplified with these primers has been sequenced in all species of the virilis group).