Pupal height

We have noticed that the positional height of simulans pupae in standard media vials is low compared to melanogaster. After establishing isolines from wild-caught females, the general pupal height in each vial is a strong predictor of species.

The image below shows three melanogaster and three simulans isolines from Hinnant Farm in South Carolina, two weeks after initiation. Notice that the simulans pupal cases are restricted to the tissue paper at the bottom of the vial.

Pupal carpet

In vials without anything to crawl up on, simulans larvae may deposit a carpet of pupae on the food. These cultures may have lower viability, and in the first week of eclosion, the number of adult flies may also be a good predictor of species. In the images below, you can see that both the melanogaster and simulans larvae have pupated up on the plastic, but the simulans vials have many more pupae carpeting the food surface.