368 ECONOMIC ZOOLOGY AND ENTOMOLOGY 



and tuberculosis, is sure. That they may aid in distributing 

 others is highly probable. Mosquitoes and house-flies will be 

 feared in the not far distant future as venomous snakes are 

 now. And they will be fought even more vigorously, for 

 their abundance makes them immensely more dangerous. 



Life History and Habits of Mosquitoes. Mosquitoes lay 

 their eggs in water, or in places where water is apt to accumu- 

 late. Some species fasten the eggs together in little masses 

 that float on the surface and look like small particles of soot at 



\ 



FIG. 156. Mosquito eggs and larvae, Theobaldia incidens; two larvae 

 feeding on bottom, others at surface to breathe. (Enlarged.) 



first glance. Other species lay their eggs singly, some floating 

 about on the surface of the water, others sinking to the bot- 

 tom where they remain until the young issue. In the summer 

 time the eggs hatch in thirty-six to forty-eight hours. The 

 larvae, or "wrigglers," are fitted only for aquatic life, but they 

 must obtain their oxygen directly from the air and so have 

 to come to the surface to breathe. This is an important thing 

 to remember when considering means for their control. The 

 larvae of most mosquitoes have, on the eighth abdominal seg- 



