158 



ROLAND THAXTER ON THE 



Hosts. Diptera: imagines of Culex and numerous genera of minute flies or gnats. 

 Habitat. Maine, New Hampshire, Massachusetts, Europe. 



This is apparently the smallest of all the Empusae and is reported to be common in 

 various parts of Europe. Although not previously accredited to this country, I have 

 found it repeatedly in the localities above mentioned. At Kittery, Maine, it occurred 

 early in July on very minute Diptera, adhering to the under side of the leaves of hop, 

 hollyhock and other plants growing about houses; and isolated specimens were found 

 i^i. similar positions in the neighboring woods, or marshy places. Although mosquitoes 

 (Culex) abounded in these localities, the only specimen of this insect that I have seen 

 infested with E. Culicis was found on the edge of a small brook in the alpine region of 

 Mt. Washington. In this same locality, at the head of Tuckerman's ravine, I have 

 found an insect also attacked by E. Culicis, whose reputation is perhaps worse even than 

 that of the mosquito, namely the "black fly" (Simulium molestum). These specimens 

 were also found upon the under side of leaves, as in the case of the examples from Kit- 

 tery; although in Europe the more usual habitat seems to be such moist situations as are 

 afforded by the margins of brooks or the borders of tanks, in which, also, infected spec- 

 imens may often be found floating. 



The form described by Sorokin as E. rimosa seems certainly to belong to this species, 

 as has been pointed out by Nowakowski, although Sorokin, in his later publications, still 

 adheres to the opinion that his species is distinct. In describing E. rimosa, 1 Sorokin 

 states that the host is attached by rhizoids, and that the conidiophores appear on the 

 thorax, seldom on the abdomen of the hosts, producing bell-shaped conidia of which, so 

 far as I have seen, he gives no measurements in any of his publications. The resting 

 spores he describes as of irregular outline, produced laterally on internal hyphae, which 

 subsequently thicken, contract and, bursting the body of the insect, assume a vertical 

 position on the outside. He also remarks that, from the brief description of A. Braun, 

 it is difficult to say how far the two species {E. rimosa and E. Culicis) are distinguished. 

 The figures of Fresenius from material received from Braun are, however, good, and 

 correspond to those of Sorokin in Cohn's Beitrage. 2 



As regards the " stroma," which Sorokin describes in this species, I have been unable 

 to satisfy myself; but where the fungus has developed with tolerable luxuriance I have 

 found a condition very like that which he describes; namely, a mass of septate, anas- 

 tomosing, empty hyphae filling the body of the insect. In other cases, however, I have 

 observed the presence of spherical hyphal bodies or of chlamydospores (fig. 15), which ger- 

 minated and, after more or less branching, produced conidiophores in the usual way. The 

 resting spores are unknown to me, although I have frequently found small flies contain- 

 ing resting spores in company with the conidial form. In these cases the constant as- 

 sociation with specimens of E. sphaerosperma on similar hosts has made it impossible 

 to determine to which species the resting form belonged. According to the description of 

 Sorokin above quoted the resting spores would seem to be quite peculiar; yet Nowakow- 

 ski figures spores of the usual type borne terminally on long hyphae. 



1 1. c. C, p. 231. 2 1, c. B, Taf. xni, figs. 16-18. 



