268 ] The Wonderful Ways of Insects and Spiders 



How Flies Walk Upside Down: You can observe, too, how a fly 

 crawls up walls, windows, and across a ceiling as easily as it walks 

 across the floor. Two tiny claws on the last segment of each foot 

 aid it in walking on rough surfaces. It also has on each foot two 

 small flat pads covered on the lower side with tiny hairs. These 

 hairs give out a sticky fluid which effectively holds the insect on 

 slippery surfaces and upside-down positions. It is these hairs 

 that retain the great number of germs carried by flies. 



BLOODTHIRSTY MOSQUITOES 



As in the case of the bee's sting, the feature of the mosquito 

 that chiefly interests children is this insect's bite. But while many 

 bees are highly useful to man, little but trouble can be expected 

 from mosquitoes. In the humid tropics they are the dreaded 

 carriers of such diseases as malaria and yellow fever. The relatively 

 harmless and very abundant salt-marsh mosquitoes of the Atlantic 

 and Gulf coasts inflict painful bites but do not transmit disease. 

 The female mosquitoes, like the female bees, are the trouble- 

 makers; the female of most species has piercing-sucking mouth 

 parts and its thirst for blood makes it a great pest for man and 

 beast. Some males have an elongated "beak," but it is not suited 

 for piercing skin. They live on the juices of fruits and plants. 

 It is the females, too, that "sing" by vibrating thin hard projec- 

 tions that lie across their breathing pores. 



How Mosquito Eggs Develop: Mosquito eggs can hatch only in 

 water. Even small puddles are good breeding grounds. Where 

 eggs have been laid on dry land, a hard rain may provide sufficient 

 moisture for them to develop. The water must remain standing 

 long enough from two to three weeks for egg, larva, and pupa 

 stages to be completed if an adult is to emerge. If a puddle dries 

 up in less time, the insects die. 



A female mosquito lays a mass of from fifty to several hundred 

 eggs. The larvae that develop from these eggs are aptly known 

 as "wrigglers." The pupae, or "tumblers," are also lively in the 

 water and move about lashing their tail-like abdomens. Though 

 they require no food, they must have air, and frequently come 



