192 ZOOLOGY. 



Divis. 2. Brachocera, Macq. Antennae short, not having apparently 

 more than three distinct joints ; palpi one- or two-jointed. 



(Stirps 2.) NoTACANTHA, Latr. Antennae apparently composed of only 

 three joints, the last, however, being articulated ; proboscis exserted, seldom 

 inclosing more than two lancets. The structure of the mouth is very 

 incomplete, and the number of setae variable. Pupa coarctate, the skin of 

 the larva, however, nearly retaining its previous form. Fam. 3, Strati- 

 omydcB ; 4, Beridce ; 5, CaenomyidcB. 



{Stirps 3.) Tanystoma, Latr. Antennae with only three joints, ordi- 

 narily terminated by a seta {Tabanus and Midas excepted) ; proboscis 

 exserted, generally with four setae (six in female Tabanidce ; mouth obsolete 

 in AcroceridcB) ; larva with a scaly head ; pupa incomplete. Fam. 6, 

 Tabanidce ; 7, Bombyliidce ; 8, AnthracidcB ; 9, Acroceridce ; 10, EmpidcB ; 

 11, TachydromiidcE ; 12, Hybotidce ; 13, AsilidcB ; 14, MydasidcB ; 15, 

 Tlierevidce ; 16, Lep tides ; 17, Dolichopidce ; 18, Sc enopinidce. 



(Stirps 4.) Athericera, Latr. Antennae with only two or three joints, 

 terminated by a seta ; proboscis generally withdrawn into the oral cavity, 

 with two setae (four in the Syrphidce ; mouth obsolete in the CEstridce) ; 

 pupa coarctate, the skin of the larva forming an oval case. Fam. 19, 

 Syrpliidce ; 20, Conopidce ; 21, MuscidcB; 22, CEstridce. 



Section 2. Thoracocephala. {Stirps 5.) Pupipara, Latr. (Order 

 Homaloptera, Leach). Head immersed in the thorax ; claws denticulated ; 

 larva nourished in the abdomen of the mother, and not deposited until 

 after it has passed to the pupa state. Fam. 23, Hippoboscidce ; 24, 

 NycteribiidcE. 



The first section includes a great majority of the Diptera (including 

 those to which the term fly is popularly assigned), in which the head and 

 antenna? are free. The mouth is a soft rostrum, containing several bristle- 

 shaped organs in a groove along its upper surface, which also forms a 

 channel for the liquid food. 



The CulicidcB is a family of which Culex (including the mosquitoes) is 

 the best known genus, and notwithstanding their small size, their organiza- 

 tion is very perfect. The rostrum is very long and slender, apparently 

 simple, but composed of seven organs. The male, which does not sting, 

 can be readily distinguished by the feathery antennae. These tormenting 

 insects do not move about much during the day ; but where they abound, as 

 soon as the sun sets, they fill the air in myriads, and become a serious evil. 

 They abound in w^arm climates ; and in the low regions of the lower Missis- 

 sippi, they fill the houses and the cabins of the steamboats as evening 

 advances. In many parts of the United States it is necessary to exclude 

 them from beds by a netting of gauze called a mosquito bar. In districts 

 where they are rare, a house may be infected with them from a vessel used 

 to catch rain water, and in which a passing female may deposit her eggs. 

 These are laid upon the surface of stagnant water one at a time, but in 

 contact with each other, and to the number of two or three hundred. In 

 two days the larva make their appearance, in fifteen days they become 

 390 



