134 - ROLAND THAXTER ON THE 



IS^owakowski, and I am also indebted to Professor Farlow, Messrs. C. V. Riley, L. O. 

 Howard, Henry Edwards and A. F. Chatfield for several interesting specimens. To 

 Mr. C. W. Woo.dworth and Prof. S. W. Williston I also owe certain entomological de- 

 terminations. 



The plants that are to be considered in the present paper belong to a class which, al- 

 though made up of several groups differing widely from one another in their habit and 

 affinities, is yet, by reason of a peculiarity common to all its members, possessed of a 

 certain individuality of its own that renders it susceptible of a consideration apart from 

 all other forms of plant life. This peculiarity, by reason of which the class is usually 

 characterized as entomogenous or entomophytous, consists in an obligatory parasitism 

 upon insects, which, although in some instances it exists without apparent injury to the 

 insect host, is usually of such a nature as to cause its death; often resulting, especially 

 among noxious insects, in widespread mortality. 



Although a few of the more common or conspicuous forms of entomophytous plants 

 had attracted the notice of botanists even in the last century, it was not until within 

 comparatively recent years that they began to be studied with any care, and the wort 

 of Robin^ is the first contribiition of importance on the subject. This work still remains, 

 with two exceptions,^ the only attempt that has been made to bring together all the known 

 forms of insect parasites ; but since its publication very important contributions have been 

 made to our knowledge of the siibject, through the medium of numerous scattered 

 papers. 



My attention was first turned in this direction in the course of entomological studies 

 on the life-histories of certain insects ; in the course of which I was often greatly annoyed 

 by losing large numbers of larvae and pupae through the agency of fungi. Having by 

 this means and from other sources accumulated a certain amount of material, it was my 

 first intention to include in my paper all the entomogenous plants recorded from Amer- 

 ica; yet, owing to the many difficulties presented by the ascomycetous forms, involving 

 a careful study and comparison of more abundant material than I could command, as 

 well as by reason of the considerable additions to our Entomophthoreae resulting from 

 my observations, I have decided to confine myself for the present to the members of this 

 family, trusting to a future opportunity of extending my paper in conformity with my 

 original plan. In the meantime a brief summary of the more important groups may not 

 be out of place in this connection, and will be a fitting introduction to the more detailed 

 consideration of the Entomophthoreae which follows. 



Summary of entomogenous plants. — Although the spiders and myriapods are not ex- 

 empt from the attack of peculiar vegetable parasites, the hexapod insects offer by far the 

 greater number of instances of this nature. Among the seven orders of the latter class 

 usually enumerated, the IN'europtera and Orthoptera are almost wholly free from such 

 attack; and, imtil recently, the first named order was considered wholly exempt in this 

 respect. Of the remaining orders the Lepidoptera and Diptera are apparently the great- 

 est sufferers; while the Hemiptera, Coleoptera and Hymenoptera are about equally af- 



> C. Robin, I. c. that are known to form the bases of fungoid parasites, 



''Sorokin, I. c, C, and Gray, G. R: Notices of insects London, 1858. 



