This morning I was helping a friend over at his place, and the BSF were swarming all over. Never seen that many in 1 place. They were landing all over us. At my place, I have seen maybe 4 in the last 3-4 years.
Speaking of wasp, years ago we used to buy "Wazp Larva" for fishing bait. I know what wasp larvae look like, and those were not wasp larvae. I also know what fly larvae look like, and they appeared to be some type of fly larvae. Are you familiar with that trade name? Probably BSF larvae, no?
Hey there bobad,
I'm not sure what to think of your experience. How confident are you that the flies at your friend's place were BSF? Both the swarming and the fact that they were landing on you makes me doubt they were BSF.
Up until a few weeks ago I hadn't seen more than about a dozen BSF adult flies at one time, and I've released 10's of thousands of larvae on my property. Then recently I had several thousand pupae in a bucket and one morning there must have been around 200 newly emerged BSF adults clinging to the inside walls, drying their wings. I continued working in the area and the BSF all eventually came out of the bucket and flew straight into the woods. Not one landed on me or showed me any attention at all.
I should point out that I do have BSF land on me occasionally but that's to be expected because I often have the scent of the grubs on my hands and this is a powerful attractant to egg laden females.
I'm trying to imagine what would motive BSF to swarm and I can't come up with anything. If these would have been newly emerged adults they would be mating and I've never heard of this happening in a swarm. I suppose it's possible but I think it would require a huge BSF population. As I understand it a male and a female couple in flight and usually fall to the ground together. If these were mating BSF I think you would have noticed this. If these were BSF that had already mated then they would have been all females looking for an egg laying site. In that case you would still need a huge BSF population and also a super attractive food source. In any case I can't imagine that many BSF anywhere unless there was a very large food source.
I don't know bobad, I respect your ability to observe nature, but on the other hand this is unusual behavior for BSF and there are over 100,000 species of flies after all. One thing you could do is check back at your friend's place in about two weeks and look for BSF grubs. Assuming there is ample food available the grubs should be very easy to find.
For more information you can read this study about BSF mating behavior done by Doctors Sheppard and Tomberlin, two of the leading BSF researchers: http://www.fcla.edu/FlaEnt/fe84p729.pdf In this study they did observe large concentrations of BSF adults, but the location was an open-sided chicken house. BSF thrive in chicken manure which explains the large numbers in that case. BSF are typically welcome in a situation like this open layer house because they reduce house fly breeding almost entirely.
If you get more information about this I would be interested.
About the Wazp Larva; I agree they were probably BSF. In certain areas BSF grubs are very popular as bait, especially in the south where they're easy to culture.
