THE INSECTS OP SEPTEMBER. 217 



cold. Hence the whole insect population is busied late in the 

 month in looking out snug winter quarters, or providing for the 

 continuance of the species. Warned by the cool and frosty 

 nights, multitudes of caterpillars prepare to spin their dense 

 silken cocoons, whicji guard them against frost and cold. Such 

 are the "Spinners," as the Germans call them, the Silk moths, 

 of which the American Silk worm is a fair example. The last 

 of September it spins its dense cocoon, in which it hibernates 

 in the chrysalis state. 



The larvae of those moths, such as the Sphinges, or Hawk 

 moths, which spin no cocoon, descend deep into the earth, where 

 they transform into chrysalids and lie in deep earthen cocoons. 



The wild bees may now be found frequenting flowers in con- 

 siderable numbers. Both sexes of the Humble bee, the Leaf- 

 cutter bee, and other smaller genera abound during the waim 

 days. ^ 



One's attention during an unusually warm and pleasant day 

 in this month is attracted by clouds of insects filling the air, 

 especially towards sunset, when the slanting rays of the sun 

 shine through the winged hosts. On careful investigation these 

 insects will prove to be nearly all ants, and, perhaps, to belong 

 to a single species. Looking about on the ground, an unusual 

 activity will be noticed in the ant-hills. This is the swarming 

 of the ants. The autumnal brood of females has appeared, and 

 this is their marriage day. 



The history of a formicarium, or ant's nest, is as follows : The 

 workers, only, hibernate, and are found early in the spring, 

 taking care of the eggs and larvae produced by the autumnal 

 brood of females. In the course of the summer these eggs and 

 larvae arrive at maturity, and swarm on a hot sultry day, usually 

 early in September. The females, after their marriage flight, 

 for the small diminutive males seek their company at this time, 

 descend and enter the ground to lay their eggs for new colonies, 

 or, as Westwood states, they are often seized by the workers 

 and retained in the old colonies. Having no more inclination 

 to fly, they pluck off their wings and may be seen running about 

 wingless. 



Dr. C. C. Abbot gives us the following account of the swarm- 

 ing of a species in New Jersey : "On the afternoon of Oct. 6th, 

 at about 4 p. M., we were attracted to a part of the large yard 

 surrounding our home, by a multitude of targe sized insects 



