Once the lights go out, female fireflies apparently prefer a little more substance and a little less flash. Infrared imaging and other techniques have been used to monitor firefly behaviour and to show that the females of the species tend to choose mates that they perceive as able to deliver a large “nuptial gift” a high protein sperm package that helps females produce more eggs.
The team used programmed LED lights to simulate male firefly flashes. The team exposed one group of females to a flash pattern that earlier research had shown was highly attractive to females; second group saw only “unattractive” flash patterns. They also divided the males into two groups: those who had a large spermatophore to present, the virgins, and the experienced old-timers who had a smaller package. They then used IR lamps to shed light on the antics of their frisky fireflies and DNA paternity testing to figure out which males were most successful after dark.
You can read more about the research in my 1st July infrared news story on SpectroscopyNOW.com