One of the great things about traveling with other people is that you get to see new ways of doing things. This includes new ways (for me) of collecting flies.
Dalton brought along a Shannon trap, named after the dipterist R.C. Shannon. Dalton’s version is a big, 8′ x 8′, fine mesh box that is open underneath. It is suspended in the air by stakes and string, with just a couple of inches clearance above the ground. Under the trap goes the bait, and this is the mind boggling thing.
For bait, Dalton used: a whole fish, chicken parts, raw beef, flour, vegetables, fruit, and onions, all heaped together in a one meter square under the center of the trap. The idea is that insects are attracted, and then when they try to escape, they fly upwards and are caught in the trap. The collector could visit the trap, get inside it, and collect what they want.
Well, this trap, after a few days of bait ripening, was a seething mass of flies, moths, and butterflies. It may seem strange, but butterflies and moths are strongly attracted to decaying organic material, just like the flies. One of the most common moths here right now is a beautiful day flying uraniid moth, and we had to fling handfuls of them out of the trap in order to see anything else. Dalton got in and swept around with his net to clean out the flies, but after he was done I was able to photograph some of the leftovers on the reeking pile of decay. Here are a couple of the insects that were attracted.
Also present, as you might imagine, were fly larvae, or maggots. Some of the attracted beetles were busily gobbling them up, but see what happens to the predatory staphylinid beetle in the video below.