THE FALL WEB-WORM. 



53 



but in vain. Once a larva had just started to make a cocoon, but it 

 was prevented from finishing it by a secondary parasite, and it died. 

 Another larva had already 

 spun the rough outside co- 

 coon, but became detached 

 and dropped out of the low- 

 er orifice, and commenced a 

 new one. The larva, sus- 

 pended by the mandibles, 

 evidently spins at first 

 loose, irregular, horizontal 

 loops around its body, until 

 a loose cradle is formed. 

 The silk secreted for this 

 purpose hardens very rap- 

 idly when exposed to the air. 

 When secure inside this 

 cradle it lets go its hold 

 with the mandibles, and 



Fig. 24. 



■Meteorus hyphantrice : 

 larged). 



female ; 



cocoon (en- 



finishes the soft inside cocoon in the usual manner. If the larva has 

 dropped to the ground it still makes an outer loose cocoon, but the 

 silken threads are thicker and much more irregular. In cocoons made 

 during a high wind the threads that suspend them are much longer, 

 reaching sometimes the length of 4 inches; the more normal length 

 varies from 1£ to 2 inches. 



'•To find out the length of time which this insect occupies in matur- 

 ing inside the cocoon, 44 freshly -made cocoons were put in a glass 

 jar. With a remarkable regularity but ten days were consumed by the 

 insect in changing from the larval to the winged form. The winged 

 MeteoruB issues through a perfectly round hole at the lower end of the 

 cocoon by gnawing off and detaching a snugly-fitting cap. There are 

 several secondary parasites of the Meteorus which we may mention later, 

 and they always leave the cocoon of their host by smaller holes cut 

 through the sides. Most of the adults had issued by the first of Novem- 

 ber, but it is possible that some may remain in their cocoons until spring. 



k - In order to obtain the proportion between the Meteorus raised from 

 cocoons and its parasites, i. c, secondary parasites of Ryphantria, 450 

 cocoons were confined in a glass jar the latter part of September, dp 

 to the first week in November only 70 specimens of Meteorus were bred 

 from these cocoons, the pest giving out secondary parasites, which con- 

 tinued to issue up to date of writing (December 20, 1886). Thus, only 

 li) per cent, of the cocoons produced the primary, while 84 per cent. 

 produced secondary parasites." 



Apanteles hyphantrice Riley (Fig. 25 represents a closely allied spe- 

 cies). — "This insect was about as numerous as the Perilitus communis. 



