A sieve of the type used for soils is dusted with baby powder to prevent ants from crawling out.
The ants are put through a sieve to sort them into size classes of large and small ants. The phorid fly Pseudacteon tricuspis develops into a male from an egg laid in a small ant and into a female from an egg laid in a large ant. The lab uses a precise mix of large and small ants in the attack arenas to produce a majority female population and thus maximize production of the females.
A lab tech (wearing gloves!) helps to move the ants and brood through the sieving process.