PHYLUM ARTHROPODA. INSECTS 



243 



Figure 142. Millions of mayflies swarmed up from the river in St. Paul, Minnesota, to 

 "plaster" lighted objects in the area. An attendant at a gas filling station covered his head for 

 protection while servicing cars. The next morning, the short-lived flies were piled up seven 

 inches high around the station. Their dead bodies were removed from the premises with a 

 snow pusher. (Courtesy of Wide World Photos.) 



the cockroach secretes an egg case to pro- 

 tect her eggs; the larvae of flies are known as 

 maggots; and certain species, especially cer- 

 tain hymenopeterans, stimulate the forma- 

 tion of plant galls in which the larvae live. 



ADAPTIVE MODIFICATIONS 



The wings, legs, mouth parts, antennae, 

 digestive tract, and respiratory system are 

 among the structures most conspicuously 



