GYPSY AND BROWN-TAIL MOTHS. 43 



egg to adult. It is very probable that the adults live for a long 

 time, like those of Monodontomerus, and they may hibernate. 



Monodontomerus aereus. 

 The females (Fig. 18) deposit their eggs (Fig. 19) in the 

 freshly formed pups of the gypsy moth and of the brown-tail 

 moth, several in each individual host. The larvse (Fig. 20) feed 

 and subsequently undergo aU of their transformations within 

 the pupal shell, of which they usually consume the entire con- 

 tents. (Fig. 21.) A little later than the time when the moth 

 would have issued, had the parasitized pupa remained healthy, 

 the Monodontomerus adults escape through a small hole in the 

 dried pupal shell. (Fig. 22.) From 5 or 6 to 15 or 20 come 

 from each. The males die soon after, but the females live all 

 winter, and are not able to deposit eggs for another generation 

 until the summer following. When cold weather approaches 

 they seek the shelter afforded by the hibernating webs of the 

 brown-tail caterpillars, and remain well protected in the silken 

 chambers during the winter. They come forth in the spring as 

 soon as the weather becomes warm enough to stir them into 

 activity, and in the course of the period intervening between 

 their resumption of activity and the pupation of the brown-tail 

 and gypsy, they develop their eggs and are ready for the attack. 

 A considerable number of the adults of this parasite, all, with- 

 out exception, fertilized females, issued from the large number 

 of brown-tail hibernating nests which were imported from vari- 

 ous European countries during the winter of 1905-06. A part 

 were given their freedom in the spring, but as it was soon found 

 that the species were not in any way an enemy of the hibernating 

 brown-tail caterpillars, and as their parasitism of the pupse of 

 the gypsy moth and brown-tail moth was not indicated at that 

 time, their liberation was discontinued. In 1906 and 1907 

 small numbers were reared from imported cocoon masses of 

 brown-tail, but under conditions which told nothing concerning 

 their host relations. Upon several occasions small numbers have 

 been reared from the puparia of Tachinid parasites of the gypsy 

 moth, and it was feared that the parasite might prove to be 

 habitually secondary, instead of primary. 



Like Chaleis, Monodontomerus is more common in southern 



