Aster World, Part 6: Bright Iridescent Flies

 Flies came to the asters in droves!   Here are the brilliantly colored Secondary Screwworm Flies (Cochliomyia macellaria):

Secondary Screwworm Flies came 

in great numbers to feed on Hairy Asters, 

Geary County, Kansas, October 6-15, 2021.

These flies are part of the cleanup crew!   The females lay their eggs on carcasses, so the maggots can feed on carrion, transforming decaying flesh into living tissue.  The maggots will also eat necrotic tissue, helping to clean wounds.  These flies are called "secondary" because unlike some other Blow Flies, they will not inflict primary wounds but only clean up existing ones.    They can transmit diseases from one animal to another, but as decomposers they play a beneficial role.

It's the maggots that eat carrion.   Here the adults are feeding on nectar and pollen.

A second species of bright metallic fly also came to the asters in October.   This one looks like the Secondary Screwworm Fly, except the final abdominal segment is bronze, not green, and the thorax is solid green, not striped.   Some think this species is the Green Bottle Fly, also in the Blow Fly family.   Others believe it to be in the Housefly family (Muscidae), due to the modest bristles.  Green Bottle Flies have prominent bristles!   Here is this species in action:  

Shiny iridescent fly, on volunteer Hairy Asters.

Geary Co., Kansas, October 5-20, 2021.