176 ROLAND THAXTER ON THE 



otherwise be disti-ibuted among at least four other species having spherical resting spores 

 and growing upon aphides, namely, -S. spTiaerosperma, E. occidentalis, E. PlancJioniana 

 and the form under consideration. I have, it will be noticed, placed JE. ferruginea as a 

 synonym of this species, although Mr. Phillips states that his species, in the opinion of 

 Mr. Cook, is a distinct form, as shown by a comparison with authentic specimens of !]• 

 Aphidis. The figures and descriptions oi E. ferruginea, however, as far as T can judge, 

 point to the present species; and moreover the exsiccati specimens of E. Aphidis are 

 luireliable, the two numbers that I have examined^ containing in the one instance nothing 

 whatever, and in the other E. Fresenii, a species which cannot be confounded in any 

 way with E. Aphidis on account of its peculiar resting spoi-es. 



Although this species {E. Aphidis) has not, to my knowledge, been previously reported 

 from the United States it is, with the exception of E. Mascae and perhaps E. Qrylli, the 

 commonest of all the Empusae; occurring abundantly in the localities above mentioned. 

 It was first called to my notice by Dr. Greorge Dimmock who noticed it in a greenhouse 

 in Cambridge during the winter of 1886. In this situation it acted as a decided check 

 to the multiplication of the aphides, yet did not spread with sufficient rapidity to render 

 "smoking" in the greenhouse unnecessary. At Kittery I have found it on niimerous 

 genera of aphides and especially destructive to the forms which injure the hop. In one 

 case I observed a large hop vine some twenty feet high completely covered with aphides 

 which were killed ofi" by this fungus in about two weeks; the afiected hosts being fas- 

 tened to the under sides of the leaves, and to the younger shoots in vast numbers. The 

 destruction of colonies of Aphis by this species or by E. Fresenii seems to be the rule 

 rather than the exception, and is at least of very common occurrence. An instance of 

 the kind was called to my attention during the second week in June of the past year 

 (1887) by Mr. L. O. Howard, who showed me great quantities of aphides dying of the 

 disease on clover near the agricultural department buildings in Washington. The prob- 

 able agency of ants in spreading these epidemics is worthy of notice as well as that of 

 night moths, especially Noctuidae, which, as well as ants, are often attracted in great 

 numbers by the sweet secretion of the aphides. 



Despite the abundance of the conidial form, I have never obtained a single specimen 

 of the resting spores that I have been able to discover among my material. The conidial 

 form is chiefly of interest from the peculiar "germination" of the hyphal bodies repre- 

 sented in fig. 239, and consisting in the production, from a central cell with a highly re- 

 fractive contents, of a mass of hyphae growing from it in all dii-ections, and subsequently 

 giving rise to the conidioj)hores. This at least is the usual derivation of the mass of 

 contorted and branched hyphae which may be found fiUing the aphides just before the 

 external appearance of the conidiophores. The number of these cells or hyphal bodies is 

 small, as may be inferred from the enormous number of hyphae which each produces, 

 and their origin is a question which I have been unable to settle from actual observa- 

 tion ; although in a few cases I have found large hyphae at a less advanced stage of the 

 development of the fungus, the contents of which were collected terminally or intersti- 

 tially into rounded masses which may have represented the hyphal bodies in question. 



The conidia are noticeable from their considerable range of variation, both in size and 



'Myc. Univ. No. 1916; Herb. Myc. No. 768. 



