Stalk-eyed fly

Diopsidae

Diopsid flies are certainly some of the strangest-looking insects, with the extreme modification of the head into two long stalks lending them an other-worldly appearance. Perhaps even more interesting is the evolutionary mechanism underlying this bizarre anatomy, whereby female flies show a strong preference for males with larger eye-stalks. This so called sexual selection is also the process responsible for development of exaggerated ornaments in other animals, such as the peacock’s tail feathers.

Collector: William F. Snow
The Gambia, 1972

Specimen collecting becomes easier when there are already established institutions and relationships in a range of countries. One such British colonial institution is a medical research unit formed in The Gambia in 1947 by the Medical Research Council UK. The unit worked with British researchers studying tropical diseases. Although the stalk-eyed fly is not a disease carrier itself, it was collected by William Snow during his time at the medical unit. Snow subsequently donated all his insects to the Museum.