16 PARASITOLOGY. 



The antennae are composed of segments (joints 

 or articles) which vary in number according to the 

 species. 



The mouth parts are provided with a proboscis 

 for piercing the skin and sucking blood, or with an 

 apparatus for sucking up liquid substances. 



The thorax of those belonging to the order Diptera 

 is provided with three pair of legs and one pair of 

 wings. Those we study under the orders Hemiptera 

 and Siphonaptera are provided with three pair of 

 legs only. 



With regard to reproduction, the female may lay 

 the ova, larva, or ova containing the larva fully de- 

 veloped. 



The insect laying the ova is called oviparous 

 (ova — egg, parous — to bring forth). 



The insect producing the larva is called vivipar= 

 OUS (vivo — living, parous — to bring forth). 



The parasite producing the egg with the larva 

 fully developed within is called ovoviviparous 



THE FLIES. 



Mosquitoes — (Musca — fly, ito — small.) 

 History. — Mosquitoes are found in all parts of the 

 world, from the cold countries of the north to the 

 hot countries of the south. One hundred and fifty 

 species have been described. More than thirty spe- 

 cies are found in the United States. Among the 

 common species may be named the Culex Pungens, 

 Culex Pipiens, Culex Equinus, Stegomia Fasciata, 

 and Anopheles Punctipennis. 



Description. — Mouth parts provided with lancet-like 

 piercing mandibles ; long, slender body ; delicate, 



