CHINCH BUG WEST OF MISSISSIPPI RIVER. 41 



infested with chinch bugs, and it is on this fungus that most observa- 

 tions have been made. 



The genus Sporotrichum includes a large number of fungi, the most 

 of which are purely saprophytic (i. e., living on dead animal or vege- 

 table tissues). According to the best information obtainable, some 

 of these are known to attack living tissues, causing their death, but 

 afterwards developing rapidly on the body of the dead host. Sporo- 

 tricJium globuliferum belongs to the latter class, and is known to occur 

 on insects belonging to the orders Coleoptera, Lepidoptera, He- 

 miptera, and also on myriapods (centipedes and millipedes). It is 

 credited with effectively attacking the elm leaf-beetle, the pupae and 

 adults of which are found covered with the fungus, especially in late 

 summer of a moist season. a 



Attempts have been made in most of the Central-western States 

 to grow this fungus under artificial conditions, and then introduce 

 it into fields badly infested with chinch bugs, where the fungus is 

 not known to be present. With the possible exception of the Kansas 

 experiments, made by Dr. Snow in the early nineties, these attempts 

 met with little success. In most cases some unfortunate circum- 

 stance always arose to make the success of the experiment uncertain. 

 (This fungus requires rather cool, moist weather for most rapid 

 development, and is present in greatest profusion when the bugs are 

 exceedingly plentiful and massed together.) In many of the early 

 attempts at artificial introduction, Entomophthora was present as 

 well as Sporotrichum, thus giving rise to> some confusion concerning 

 just which fungus was credited with actually killing the bugs. 



The most important of these experiments are fully set forth in 

 the reports of the State entomologist of Illinois and in Bulletins 15 

 and 69 and Circular 113 of this bureau, and therefore require no 

 extended discussion here. 



OBSERVATIONS BY THE WRITERS. 



FIELD STUDIES IN KANSAS AND OKLAHOMA. 



It is fully realized by the writers that the determination of the cause 

 of a disease is most difficult, and that it requires extended laboratory 

 research along many different lines. To state that this fungous disease 

 is the cause of the mortality among the chinch bugs, without this 

 extended laboratory investigation, would be entirely unscientific. 

 The observations given here are published for what they are worth. 



Observations on the habits and occurrence of the fungus were made 

 in Kansas and Oklahoma during the spring of 1908 and 1909, and 

 the spring and summer of 1910. Some additional data were obtained 

 with respect to its behavior in the field among chinch bugs of all ages 



a Conn. Agr. Exp. Sta., Bui. No. 155, 1907. 



