ARTHROPODA 193 



Their larvae live in the soil and injure the roots of plants. The 

 midges {Chironomidae) are small flies somewhat resembling mo- 

 squitoes. In the larval state they are red, wormlike, aquatic forms. 

 The black flies {Simuliidae) are aquatic in the larval state, and the 

 adults are great pests in some localities since they are blood suckers 

 and attack fishermen. 



T\\& fruit flies, particularly the Drosophilidae (Fig. 90), are used 

 in investigations on heredity. (See p. 538.) There are about 

 1,000 species of Trypaneidae attacking various fruits. The Mediter- 

 ranean fruit fly ^ {Ceratitis capitata), known for over 100 years, and 

 of considerable importance in the Mediterranean countries and 

 more recently in Hawaii, was discovered in Florida on April 6, 1929. 

 Its life cycle takes from 30 to 40 days, pupation occurring in the 

 ground. In Hawaii and in South Africa, Ceratitis capitata has 

 proven a serious pest of the citrus fruits, but also attacks deciduous 

 fruits such as peaches and apricots. Lemons are practically im- 

 mune to this pest, but sour oranges are more susceptible than the 

 sweet varieties. In Hawaii, poison sprays have not been used with 

 any degree of success, but they 

 appear to be more effective in 

 the U. S. 



The Syrphus flies {Syrphi- 

 dae) are important enemies of 

 the aphids and feed on nectar 

 and pollen. Some are scaven- p^^ ^^ ^ "rat-tailed" larva (Syr- 

 gers, the " rat-tailed " larvae phidae). (Smith, Insects of New Jersey, 

 feeding on foul organic matter. N.J. Board of Agr.) 

 (Figure 91.) 



Some of the species " mimic " the bees and wasps. According 

 to the ancient Bugonia myth, bees develop in the carcasses of dead 

 animals, but the drone-flies {Eristalis tenax) are the forms thus 

 found. The reactions of the drone-fly to light have been extensively 

 studied by Dolley.^ 



8 In climates where the mean temperature fails below 50° F. over periods covering 

 3 months, there is little development of Ceratitis capitata and accordingly it is hoped 

 that we can limit its ravages to the Southern states. (Herrick, G. W. The procession 

 of foreign insect pests. Sc. Mon., vol. 29, pp. 269-274.) 



'W. L. Dolley, Jr., and J. L. Wierda. 1929. Relative sensitivity to light in 

 different parts of the compound eye in Eristalis tenax. Jour. Exp. Zool., vol. 43, pp. 

 129-139, May. 



