PARASITES HIBERNATING IN BROWN-TAIL WEBS. 269 



In the spring of 1906 some 40 large tube cages (PL X, fig. 1), each 

 capable of accommodating several thousand nests, were constructed 

 after the model of a cage which had been successfully used for a some- 

 what similar purpose in California. Hardly had the nests been placed 

 in these newly constructed cages before the caterpillars began issuing 

 in extraordinary numbers, and with them many thousands of adult 

 parasites, representing a great variety of species. Monodontomerus 

 sereus was about the first to issue, and with it was a quantity of 

 Habrobracon brevicornis. A little later Pteromalus egregius (fig. 65) 

 appeared in an abundance which exceeded that of all the other para- 

 sites taken together, and it was followed shortly afterwards by 

 swarms of its own little parasite, determined by Dr. Ashmead as 

 Entedon albitarsis. 



Fig. 65. — Pteromalus egregius: Adult female. Greatly enlarged. (Original.) 



Mr. Titus at once recognized Entedon as hyperparasitic and pro- 

 ceeded as assiduously to destroy it as he was assiduous in saving the 

 Pteromalus. Of the myriad of other parasites issuing, the vast 

 majority were represented by so few individuals as to render it very 

 improbable that any among them were enemies of the caterpillars of 

 the brown-tail moth. Nearly all of the more common species, aside 

 from Pteromalus and Entedon, were representative of genera or 

 groups of genera well known to be parasitic upon Cynipidse, of which 

 large numbers issued from the galls on oak leaves that had been used 

 by the caterpillars in the construction of their nests. There remained 

 as possible parasites of the caterpillars of the brown-tail moth only 

 Habrobracon brevicornis, Pteromalus egregius, and Monodontomerus 

 sereus. 



It looked for a time as though the Habrobracon might be para- 

 sitic upon the hibernating caterpillars, and quite a large number of 



