178 



ROLAND THAXTER ON THE 



Empusa (Entomophthora) virescens nov. sp. 

 PI. 18, figs. 251-261. 



Conidia ovoid to oblong, of irregular shape; with bluntly rounded base and apex, the 

 former often hardly papillate and not well distinguished from the apex : color greenish yel- 

 low in dried material ; containing numerous small, irregular, often rod-like fat bodies; 

 measurements 10x20,^-16x36//, average 11x30;/. Conidiophores digitate, arising indi- 

 rectly from spherical hyphal bodies which germinate in all directions, giving rise to very 

 numerous hyphae which subsequently become conidiophores. Cystidia not observed. 

 Secondary conidia like the primary. Resting spores unknown. Host attached to sub- 

 stratum by rhizoids? 



Hosts. Lepidoptera: larvae of Agrotis fennica. 



Habitat. Ottawa, Ontario (Mr. Fletcher) . 



The specimens from which the above description was taken were received by Professor 

 Farlow from Mr. J. Fletcher, Dominion entomologist, who writes concerning them as 

 follows: — "In the spring of 1884 from May 15 until the end of the first week in June, 

 all the gardens and fields in the district around Ottawa were severely attacked by the 

 larvae of Agrotis fennica. The disease of which you have a specimen was first observed 

 about the 22nd of May, and was extremely virulent. Dead larvae were to be found in 

 all directions; on stone walls, on fences and particularly on the tops of steins of grasses. 

 They were also vigorously assailed by Tachinidae and Carabidae. The Entomophthora, 

 however, was undoubtedly the influence which brought this insect down again to its 

 normal rare occurrence at Ottawa." The specimens received were black and shrivelled, 

 the fungus appearing as a greenish yellow coating, emerging in small tufts, which, in the 

 more mature specimens, appear to have coalesced over the body. The conidia appear 

 also greenish yellow in the mass, and are recognized by their general shapelessness and 

 rounded extremities, as well as by the numerous small fatty bodies of a crystalline ap- 

 pearance which characterize the spore contents. I have placed this species near E. Aphi- 

 dis from the structural similarity indicated by the peculiar germination of the hyphal 

 bodies already described in the last-named form; but the conidia seem to be of a different 

 type. 



It should be noted that the host of this species is closely allied to that of E. mega- 

 sperma of Colin which also occurs upon an Agrotis larva. Mr. Fletcher writes me that 

 he has not observed a single specimen of the fungus since the date above mentioned, and 

 as the material originally sent contained only conidia I am unable to give any information 

 concerning the resting spores. The conidia of E. megasperma are unknown, nor has the 

 species been observed to my knowledge since it was described by Cohn. 2 The resting 

 spores of E. megasperma are fortunately an exception to the general rule, being readily 

 recognized by their dark brown, reticulate epispore, so that the question concerning the 

 identity of the present form with Conn's species can be settled beyond a doubt as soon as 

 the resting spores of the one or the conidia of the other become known. 



1 l. c. B. 



