Stalk Eyed Fly Facts
- The Stalk Eyed Fly represents one of those insects that display a rather extreme difference between the genders. In their case, it’s because the eyestalks of the males have evolved as greatly elongated.
- By evolving such extended eye stalks, the species has also developed an extreme advantage over related species. As a result of the unusual placement of the eyes, they actually have binocular vision.
- The fact that males do not display them at birth remains the most noteworthy aspect of the eye stalks, however. From the moment of birth, they ingest air through their oral cavity, and pump it through ducts to the stalks, thereby elongating them over time.
Stalk Eyed Fly Physical Characteristics
The number of known species of Stalk Eyed Fly in the world totals approximately 100. All of these tend to be either small or medium-sized, in relation to other flies. As a result, their sizes range from 0.15-0.45 in (4-12 mm) in length.
Their heads develop rather small compared to other flies, and somewhat triangular in shape. Also, any hair on the head develops sparsely.
The most noteworthy attribute of the Stalk Eyed Fly, as the name implies, will always be the highly elongated eye stalks. These actually stay soft and elastic, until the pupae begin “inflating” them, shortly after birth.
Stalk Eyed Fly Distribution, Habitat, and Ecology
The various species of Stalk-Eyed Fly inhabit a wide range, yet the majority of these occur in the “Old World” tropics. Most occur in Southern Africa and Southeast Asia. A few occur in both North America and Europe. Typical habitats include areas of low-slung vegetation and regions of high humidity.
Another requirement for habitation appears to be proximity to streams and rivers. They primarily feed on the bacteria and fungi that they find on decaying vegetation. Sexual dimorphism is taken to an extreme degree by this insect since the females lack the elongated eye stalks.
These serve a purpose in sexual selection since females typically choose the male with the longest eye stalks.