456 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 5 



lated experiments by scattered workers. This is one of the uses of 

 the Poison Exponent, but it is likely that others would develop. For 

 instance, the statement of a reputable manufacturer that his new 

 preparation has a Poison Exponent of .75 to the most resistant instar 

 of the boll worm would doubtless convey in the course of time a more 

 definite idea to the mind of the entomologist than would a chemical 

 analysis, valuable though the latter might be. 



Whether the Poison Exponent is ever used or not, however, the 

 writer cannot but believe that the subject of toxic values of chemicals 

 to insects is a matter that is worthy of some consideration, and he 

 hopes that other workers will give it the attention it deserves. 



NOTES ON INSECT DESTRUCTION OF FIRE-KILLED TIMBER 

 IN THE BLACK HILLS OF SOUTH DAKOTA 



By Philip L. Buttrick, Neiv Haven, Conn. 



This paper attempts to outline the results of the work of insects 

 following forest fires in the Black Hills of South Dakota; and to suggest 

 remedies for their depredations. It is the result of casual observations 

 of the writer, made while Forest Assistant on the Black Hills National 

 Forest in 1911,. and later as Forester for the Lanphere-Hinrich Com- 

 pany, a lumber company operating in the Black Hills. The observa- 

 tions do not pretend to approach completeness; but may be of some 

 value in the absence of more definite data. 



Character of the Forest in the Black Hills. Western Yellow Pine 

 {Pimis pojiderosa) is the predominant tree. It occurs pure over large 

 areas, being the only commercial tree found. The forest tends to be 

 even-aged in groups, but many stands are all-aged or roughly two- 

 storied. The Government manages its holdings by a rough applica- 

 tion of the shelter-wood system, the intention being to come back in 

 twenty to thirty years for the second cut. 



Enemies of the Yellow Pine. Forests in the Hills have suffered 

 excessively from insects and fire. The chief insect enemy, the Black 

 Hills Beetle 1 is too well known to require description. Its depreda- 

 tions have now been controlled by natural agencies, and by cutting 

 large bodies of infested timber. A close watch is now kept by the 



I Dendrocionus pojidtrosce Hopk. 



