256 INSECT ORDERS 



Order — Diptera 



Many members of this order are referred to as flies. They have a 

 complete metamorphosis, and the larvae of many of them are called 

 maggots ; whereas those that develop in water are called wigglers. As 

 the order name indicates, they have one pair of functional wings which 

 are membranous and are used for flying. The second pair are rudi- 

 mentary and are called halteres or balancers and seem to function some- 

 what like a gyroscope in flight ; they seem to help the flies maintain 

 equilibrium in flight. The mouth parts are of the sucking type, but in 

 some species there are also jaws which bite first to draw the blood which 

 is sucked up the proboscis. They may be divided into two main groups : 

 the short-horned flies, which have from three to five segments on their 

 antennae ; and the long-horned flies, which have more than five segments. 



A. Short-horned flies. 



1. Horse flies. Horse flies are usually quite large and bite and suck 

 blood of mammals. Horses seem to be preferred, but they will bite 

 many other mammals including man when they have the opportunity. 

 Some breed in swampy regions and make life almost intolerable for 

 cattle in such regions. They may be quite annoying to bathers on 

 beaches that are near swampy areas. 



2. Robber flies. These large, swift insects catch other insects in the 

 air for their food. They destroy many harmful insects, but also catch 

 many honeybees. 



3. Bee flies. These look very much like bees in coloring and feed on 

 the nectar of flowers. The larvae are quite beneficial because they feed 

 on grasshopper eggs, grub worms, and other harmful insects that pass 

 part of their life cycle in the ground. 



4. The house fly. These are so named because they are found so 

 commonly around the house. They are one of the greatest nuisances to 

 be contended with on the farm. They reproduce readily in manure in 

 the barnyard and come into the kitchen and dining table in spite of 

 screens, flypaper, sprays, and other attempts at control. Because of 

 their unclean habits they spread serious intestinal diseases such as typhoid 

 and dysentery and rank as one of the most serious insect enemies of man. 



5. The botflies. These are covered with hairs and look somewhat 

 like bees. The larvae of these are parasites which develop within the 

 bodies of mammals. The horse botfly female lays eggs on the skin of 

 horses and horses lick them off and they develop as maggots in the 

 stomach of the horse and pass out of the horse's body when they pupate. 

 In others, such as cattle and rabbits, the eggs are laid on the skin and 



