Children of a Lesser Dungfly - the ice cream tub bait trap and the lesser dung flies

One family that's doing very well on the 2020 records is the Sphaeroceridae, or lesser dung flies. So far five species have been identified (and two not!). This is a family I have an emotional tie to (yes, really) because it was one of the first monographs (Pitkin, RES) I acquired when I moved out from hoverflies.

Sphaeroceridae
Copromyza nigrina - fish-baited trap
Crumomyia fimetaria - leaf litter
Crumomyia nitida - fish-baited trap
Crumomyia roserii - fish-baited trap
Lotophila atra - leaf litter

Sieving leaf litter is always a good way to pick up a sphaerocerid or two, but a ground-level bait trap seems like a definite winner. The elevated bottle traps don't seem to catch them - I think because these flies mostly don't get very far away from the ground. This is also a good way to pick up Heleomyzidae, of which 3 species have been found in this session using this trap . One of the species was also found in the elevated bottle trap, but all three were in the low-level trap. The trap is jammed up against a ruined wall so it's probably warmer and more sheltered down there too.

Heleomyzidae
Neoleria propinqua
Scoliocentra villosa
Suillia variegata (in leaf litter, not in trap)
Tephrochlamys rufiventris

The trap design
I took an ice cream tub and cut a cross hole in the lid. The cardboard disc "filter" lets out the stink but stops things falling into the gooey mess that once was sea bass. The disc has lobes that stabilise it but I didn't draw them. Drainage holes are also not illustrated. Any sort of tub and cereal packet could be put into service this way and is essentially recycle-able. An occasional fly has flown away but once in the trap the dung flies and heleomyzids seem more-or-less happy to sit around and be potted.

Ice cream tub, fish remnants, cardboard disc

Apart from the flies this trap has yielded about 100 Catops beetles, the only one of which I gen-detted being C.tristis. And boy does it make them crazy - lots of mating pairs. I suspect there may be more than one species of Catops present. Sadly none I've taken have shown signs of fungal infection.

A modified version of this trap (larger entrance) is going to be great for silphids at some point and changing the bait up might make it a winner for dung beetles too.

NB: I always approach this trap wearing rubber gloves!

(12/02 edit: the actual tub, which has now been in place for just over a month)