PARASITOLOGY. 17 



gauzy wings ; antennae composed of fourteen seg- 

 ments; three pair of long and slender legs; one 

 pair of eyes. 



Life Cycle. — The ova are laid in boat-shaped masses 

 on the surface of the water. The larvae are small, 

 black, worm-like bodies, with forked tails in which 

 are placed the breathing tubes. They are noted to 

 come with this end to the surface of the water for 

 the purpose of obtaining oxygen. They are found 

 in cisterns, ponds and pools of water everywhere, 

 and are commonly called wlgglers. They pass this 

 stage in seven days, if conditions are favorable. 

 The pupal stage is passed in twenty-four hours. 



The ova hatch in from sixteen to twenty-four 

 hours. 



Ariimals Attacked. — Among the species that attack 

 man and beast are the Culex Pipiens. The Culex 

 Equinus especially attacks the horse. The genera 

 Anopheles and Stegomia furnish species which attack 

 man and communicate the protozoa producing mala- 

 ria and yellow fever. 



Parts Infested, — The attack is made upon the skin, 

 principally in the evening and at night, by means of 

 the stylet of its rostrum. In piercing the skin it 

 instills a poison which produces inflammation, itching 

 and swelling. 



Prophylactic Treatme7it. — It has been suggested to 

 put fish in the ponds and large bodies of water, to 

 consume the larvae. Kerosene, one ounce to each 

 fifteen square feet of water, will prevent deposit of 

 ova. Cisterns and wells should be kept screened. 

 No tin cans or other means of providing pools of 

 water should be allowed, in which mosquitoes might 



