INSECTS. 



269 



skin of cattle; and the sheep-bot enters the cavities con- 

 nected with the nose or even the horns, producing the 

 disease known as 'staggers/ 



More familiar are the mosquitoes, which lay their eggs 

 on stagnant water. The larvae hatch out and are known 

 as 'wrigglers/ They pupate beneath the surface, and 



FIG. 88. Common house-fly (ATusca). 



finally the perfect insect emerges to make itself an unmit- 

 igated nuisance about our persons. Bad as the mosquitoes 

 were long thought to be, the recent discovery that they 

 convey to man the diseases yellow fever and malaria (p. 151) 

 places them in the category of dangerous insects and has 

 led to active efforts towards their extermination. Many 

 proposals have been made for reducing the number of 



