254 FIFTH REPORT OF THE ENTOMOLOGICAL COMMISSION. 



careful watch was kept to see how such a suspended cocoon was formed, 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 out- 

 side cocoon, but became detached and dropped out of the lower orifice, and commenced 

 a new one. The larva, suspended by the mandibles, evidently spins at first loose, ir- 

 regular, horizontal loops around its body, until a loose cradle is formed. The silk 

 secreted for this purpose hardens very rapidly when exposed to the air. Wheu 

 secure inside this cradle it lets go its hold with the mandibles, and finishes the soft 



Fig. 93.—Meteorus hyphantrice ; a, female; b, cocoon (enlarged). After Riley. 



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 ir- 

 regular. 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 maturing inside the 

 cocoon, forty-four 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 Meteoriis 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 Meteortts 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 1st of November, but it is possible that some may re- 

 main in their cocoons until spring. 



In order to obtain the proportion between the Meteoriis raised from cocoons and its 

 parasites, i. e. secondary parasites of Hyphantria, 450 cocoons were confined in a 

 glass jar the latter part of September. Up to the first week in November only 70 

 specimens of Meteoriis were bred from these cocoons, the rest giving out secondary 

 parasites, which continued to issue up to date of writing (December 20, 1886). Thus 

 only 16 per cent, of the cocoons produced the primary, while 84 per cent, produced 

 secondary parasites. 



Apanteles lujphantrm "RWej {Fig. 9^). — This insect was about as numerous as the 

 Perilitiis communis, and did equally good service in preventing a further increase of 

 the caterpillars. It appeared somewhat earlier in the season, and killed only half- 

 grown caterpillars. From the numerous old and empty cocoons in early summer it 

 was plainly seen that a first brood had been quite numerous, and that from these co- 

 coons mainly Apanteles had been bred, and not, as during the autumn, mostly 



