142 British Fungi, 



tenable. Altliougli in some instances the fungus, 

 so far as observation goes, appears to produce no 

 injurious effect on the insect host, yet in most cases 

 the death of the host is the result, and it is probable 

 that in many instances the mortality thus effected is 

 very widespread, and as the mortality often occurs in 

 insects injurious to plants of economic importance, a 

 correct knowledge of the life-history of the various 

 species of fungi forming the present group is highly 

 important. Thaxter says, " I have observed two 

 epidemics caused by this species [Empusa {Ento- 

 mophthora) Splicerosperma, Fres.], one among cer- 

 tain small flies in a wood near marshy ground at 

 Kittery, Me., where the hosts occurred in considerable 

 numbers, fixed by the fungus on the under side of the 

 lower leaves, a few feet from the ground. The 

 second instance occurred in two orchards in the same 

 locality, where the hundreds of the previously mentioned 

 epidemic were replaced by tens of thousands, the host 

 in this instance being the leaf-hopper [TypMocyha 

 mall and rosce), a pest only too well known to 

 cultivators of roses. Having first observed it in some 

 abundance on roses in a garden, I was led to make an 

 examination of adjacent apple orchards, and found the 

 lower branches of the trees literally covered with the 

 affected hosts, a dozen or more being often fastened to 

 a single leaf." ^ The same author describes Ento- 

 mophthora apldclis as producing a similar wholesale 

 destruction of the aphis so injurious to the hop 

 plant. 



2 I.e. p. 173. 



