I04 



Parasitic Arthropoda 



accomplished by spraying kerosene oil on the surface of the water, or 

 by the introduction of fish which wUl feed on the larvae. 



Detailed consideration of the 

 most efficient measures for con- 

 trolling mosquitoes is to be found 

 in Dr. Howard's Bulletin No. 88 

 of the Bureau of Entomology, 

 "Preventive and remedial work 

 against mosquitoes" or, in more 

 summarized form, in Farmers' 

 Bulletin No. 444. One of these 

 should be obtained by any person 

 interested in the problems of mos- 

 qmto control and public health. 



74. 



Mouth parts of Simulium. After 

 Grunberg, 



The Simuliidae, or Black Flies 



The Simuliidae, or black flies, are small, dark, or black flies, with 

 a stout body and a hump-back appearance. The 

 antennae are short but eleven-segmented, the wings 

 broad, without scales or hairs, and with the anterior 

 veins stout but the others very weak. The mouth- 

 parts (fig. 74) are fitted for biting. 



The larvae of the Simuliidae (fig. 75) are aquatic 

 and, unlike those of mosquitoes, require a well aerated, 

 or swiftly running water. Here they attach to stones, 

 logs, or vegetation and feed upon various micro- 

 organisms. They pupate in silken cocoons open at 

 the top. Detailed life-histories have not been worked 

 out for most of the species. We shall consider as 

 typical that of Simulium pictipes, an inoffensive 

 species widely distributed in the Eastern United 

 States, which has been studied especially at Ithaca, 

 N.Y. (Johannsen, 1903). 



The eggs are deposited in a compact yellowish layer 

 on the surface of rock, on the brinks of falls and 

 rapids where the water is flowing swiftly. They are 75, ^^„^ ^f gimu- 

 elongate ellipsoidal in shape, about .4 by .18 mm. AftirSi'rman; 

 As myriads of females deposit in the same place the 

 egg patches may be conspicuous coatings of a foot or much more 

 in diameter. When first laid they are enveloped in a yellowish 



