JUNE
2003

 

 

 

By
Tom Turpin
 
Professor of
Entomology
Purdue University

 

 

 

 

 

06-26-03

Flies Frequent Visitors to Flowers

If it existed in the corporate world, the relationship between flowers and insects would be called a partnership. In such a relationship both sides benefit. The flower receives pollen transport; the insect gets food.

The most common type of insect in partnership with flowers is the bee. In fact, the lives of bees are dependent on food from flowers. But other groups of insects also visit flowers. Some just happen to find the flower a convenient landing place, but others feed there.

Some types of flies are commonly found on flowers. Unlike bees, flies found on flowers live two distinct lives. The adults feed on nectar and pollen while their immatures feed in a totally different situation. For instance, blow flies. The name of these flies is based on the fact that their immatures feed on dead, bloated animals.

Regular old house flies are also found on flowers. While their sponge-like mouthparts won't allow these flies sip nectar or chew pollen, they are able to sop up any sweet material on the flower surface. Their larvae are found feeding in all kinds of decaying waste material.

Another fly that spends its immature stages in decaying material, including animal manure, is the soldier fly. These bright-colored flies are usually found on flowers and resemble wasps.

One of the most consistent fly visitors to flowers is sometimes called the hover fly. This name is based on its behavior of hovering in the air and then suddenly darting to another location to hover again. Hover flies are also called syrphid or flower flies. These adult flies live entirely on pollen and nectar. Their larvae are parasites of eggs and young of other insects. Because of this behavior, hover flies are good to have around the garden.

Hover flies exhibit the markings and color patterns of bees and wasps. The resemblance to these stinging insects is such that predators treat the flies with respect. It is a good example of how an insect that mimics a potentially harmful one benefits. This is protection by deception.

One of the hover flies is such a remarkable mimic of honey bees that ancient people could not tell the two insects apart. This fly is called a rat-tailed maggot in the immature stage. That is because the larvae have a long rat-like tail that is a breathing tube. The maggot lives in pits of liquid manure or fluid from rotting animal carcasses. This is the insect that gave rise to the ancient idea that honey bees were generated in carcasses of rotting cattle.

Another type of fly frequently found on flowers is appropriately called a bee fly. Many of the bee flies are hairy and, because of this and their coloration, they resemble bees. Hence their name. The bee flies have a long proboscis, which they can use to suck nectar from the flower while they hover. Like the hover flies, the immatures of bee flies live an entirely different life from their parents. Just like the drone flies, bee fly larvae are parasites of other insect larvae and eggs.

So the bees visit flowers in order to collect food for themselves and their young. Flies, on the other hand, visit flowers to feed themselves. But in both instances, the flower benefits from its insect visitors. That is what the partnership is all about--everybody wins!

 

Writer: Tom Turpin
Editor: Olivia Maddox