Delhi Sands Flower-loving Fly


Description and biology

The Delhi Sands flower–loving fly is a very large fly, about 1 inch (3.9 centimeters) long. It is orange and brown with bands or dark brown spots on its abdomen. The fly has a long tubular–shaped proboscis (a long, flexible snout). Unlike common houseflies, the Delhi Sands flower–loving fly extracts nectar from flowers.

In this way it has a pollinating function (transferring pollen from one flower’s male parts to another flower’s female parts), like a hummingbird or a honeybee. It is also like the hummingbird in its strong flying, whether it is soaring rapidly up into the air or hovering over a flower while feeding.

The Delhi Sands flower–loving fly goes through a complete metamorphosis (pronounced met–uh–MORE–fuh–sis) in its life cycle, which means it undergoes four stages: egg, larva, pupa (cocoon), and adult.

It exists as an adult fly for only a few weeks in August and September, during which it feeds, mates, lays eggs, and then dies. Before her death, the mother will lay as many as 40 eggs an inch or two beneath the soil in a shady area.

The eggs hatch in about twelve days. The offspring will then spend the majority of their life under the surface of the sand in the larval and pupa stages. It is not known what the larva eats. The life span of the species is about two years.

Habitat and current distribution

The Delhi Sands flower–loving fly is currently found only in tiny areas in San Bernardino and River-side counties, California. The habitat is characterized by fine sandy soil, known as Delhi series sands. There are 11 or 12 known populations of the flies in these sand dunes.

History and conservation measures

Before southern California became so densely populated, the Colton Sand Dune system encompassed about 40 square miles (104 square kilometers) in the Delhi Sands region. It was the largest inland sand dune system in southern California, and the Delhi Sands flower–loving fly probably occurred throughout the system.

In the nineteenth century, citrus and grape farming was introduced to the area, and large areas were cleared of their native plants. In the twentieth century, urban sprawl (the spreading of houses, shopping centers, and other city facilities through previously undeveloped land) reached out to the area.

After widespread construction, the Colton Sand Dune ecosystem had virtually been eliminated. At most, about 1,200 acres (485 hectares) of the original habitat remain; about 98 percent of the ecosystem is gone.

All of the 11 or 12 populations of the Delhi Sands flower–loving fly live in tiny, fragmented pieces of their former habitat, and most of their native plant foods are gone. Estimates of the existing population are in the low hundreds.

In 1993, the Delhi Sands flower–loving fly became the first fly (and the seventeenth insect) to be listed as endangered under the Endangered Species Act (ESA).

The U.S. Fish and Wildlife Service proposed establishing three recovery units within the remaining ecosystem to protect eight of the existing populations. But the fly’s habitat is within privately owned lands, and the pressures from developing communities in the area, which want to clear more land for development, have remained very strong.

The federal courts, working under ESA, have stopped some urban development, notably an emergency route for a medical center, in order to protect the fly’s remaining habitat, but more construction is expected. There has been some political uproar over the idea that a fly’s fate should be placed above the pursuits of humans.

Conservationists, however, have argued that the loss of the Delhi Sands flower–loving fly is not all that is at stake: the loss of this species, should it come to pass, would signal the loss of an entire unique ecosystem, with all its biodiversity (variety of life forms).

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