212 



INSECT CALENDAR. 



senting a cylindrical structure, not unlike a small cartridge. 

 They commence hatching in March, but it requires a range of 

 temperature above 60° F. to bring them to maturity, and under 

 sucli conditions they become fledged in thirty-three days, and in 

 from three to five days after they enter upon their migratory 

 flight. 



"Their instincts are very strong. When food becomes scarce 

 at one point, a portion of them migrate to new localities, and 

 this movement takes place simultaneously over large areas. In 



\ 



264. Seventeen Year liocust. Eggs and Pupa. 



their progress they stop at no obstacle they can surmount. In 

 these excursions they often^ meet with other trains from an 

 opposite direction, when both join in one. 



"The insects are voracious, but discriminating in their choice 

 of food, yet I know of no plant they reject if pressed by hunger; 

 not even the foliage of shrubs and trees, including pine and 

 cedar." 



During this month the Seventeen-year locust (Cicada septcn- 

 decim of Linnaeus, Fig. 264) has disappeared, and only a few 

 Harvest flies, as the two other species we have are called, raise 

 their shrill cry during the dog-days. But as certain years are 



