LabBench Activity

Design of the Experiment

How to Tell the Males from the Females

The first thing you must do in this laboratory is learn to distinguish male fruit flies from female fruit flies.

male and female flies

As illustrated in the figures above, female flies generally have a long, pointed, lightly striped abdomen. The male abdomen, by contrast, is blunt and darker. Very young flies may not show this clear difference, so for more certain sex identification you should look for sex combs, dark bristles found on the inner surface of the forelimbs. Only males have sex combs.

In the following exercise you practice determining the sex of fruit flies. For each fly, select male or female in the appropriate box below. Newly emerged flies may be hard to sex from the abdomen alone. In such cases, look at the legs.

1. Is fly "A" male or female?

2. Is fly "B" male or female?

3. Is fly "C" male or female?

4. Is fly "D" male or female?

5. Is fly "E" male or female?