162 PROCEEDINGS ENTOMOLOGICAL SOCIETY 



EPIMECIS WILTII CRESSON AND ITS HOST. 



BY RAYMOND C. SHANNON, Bureau of Entomology. 



The life history of the Ichneumonicl, Epimecis wiltii Cress., as 

 far as could be ascertained, is entirely unknown. The observations 

 here presented show that its larva is an external parasite of spiders. 

 Another genus, Polysphincta, of the same family, has very simi- 

 lar habits, being also an external parasite of spiders. 



While collecting with Mr. C. Shoemaker at Black Pond near the 

 mouth of Difficult Run, Virginia, September 14, 1913, a spider, 

 (Epeira trivittata Keys.) was found which had a very small para- 

 sitic larva, probably recently hatched, upon its thorax. The 

 spider with larva attached was brought to the Museum and placed 

 in a breeding jar, where the spider soon spun a web, in which it 

 stayed. The larva grew gradually, while the spider remained alive, 

 and apparently quite healthy, until the sixth day. The larva was 

 then found to have grown to over twice the size that it had been the 

 previous day. It was now hanging by two of its prolegs to a strand 

 of the spiders web, and with its mouth thrust into the spider's 

 abdomen, was supporting the dead and collapsed body of its host. 

 The following morning it had dropped the spicier and had spun its 

 cocoon among the threads of the spider's web. The adult issued 

 eleven days later, October 1, 1913. 



CHANGES DURING QUIESCENT STAGES IN THE 

 METAMORPHOSIS OF TERMITES. 



BY THOMAS E. SNYDER, Bureau of Entomology. 



There have been several theories as to when the Iarva3 of termites 

 become differentiated to the various castes in the social organi- 

 zation, the prevalent one being that undifferentiated larvae are 

 developed to the castes by the character of the food that they re- 

 ceive. The results of Heath's 1 experiments, however, to deter- 

 mine the relation of various kinds of food to polymorphism, were 

 negative. In the case of ants, Wheeler 2 with Emery believes, "the 

 adult characters to be represented in the germ as dynamical potencies 

 or tensions rather than morphological or chemical determinants" 

 and that "nourishment, temperature and other environmental fac- 

 tors merely furnish the conditions for the attainment of characters 



1 Heath, H. The Habits of California Termites. Biol. Bull., Woods Holl, 

 vol. iv, December, 1902, pp. 47-63. 



2 Wheeler, W. M., The Polymorphism of Ants, Bull. Amer. Mus. Nat. 

 Hist., vol. xxiu, January, 1907, pp. 1-93. 



