392 



JOURNAL OF ECONOMIC ENTOMOLOGY 



[Vol. 8 



Microplitis sp. has exposed cocoons like Apanteles and probably has 

 many parasites but we have not reared any of them yet. Apanteles 

 rufocoxalis may have the same parasites as militaris but we have not 

 reared any of them from this species. It is possible that Enicospilus 

 purgatus, Rhogas atricornis, Ichneumon sp., and the Tachinids may 

 also have parasites but they pupate in the ground and are thus pro- 

 tected. We have reared no parasites from these species. 



The primary parasites are controlled to some extent by the sec- 

 ondary parasites; but the most important factors in their control as 

 well as in the control of Heliophila itself are changes in temperature 

 and humidity. And the effect of these two factors should be worked 

 out by a series of experiments conducted under such conditions that 

 the various factors can be controlled. These experiments could easily 

 be conducted with a couple of biological incubators such as are used 

 for bacteriological work in the tropics. 



A KEY TO THE CUTWORMS AFFECTING TOBACCO 



By S. E. Crumb, U. S. Bureau of Entomology 



The following key includes only the cutworms known to affect to- 

 bacco in the United States, but these include also the majority of the 

 common species affecting other crops. For this reason it has been 

 considered advisable to publish this table for the use of other workers 

 in advance of a forthcoming publication of the Bureau of Entomology 

 in which these species will be fully treated. 



The characterizations of Noctiia clandestina and of Feltia malefida 

 are based upon inadequate material, and those of Mamestra legitima 

 and Peridroma incivis as here presented might lead to some confusion, 

 owing to the fact that it was originally intended that this key should be 

 accompanied by descriptions and photographs of the larvae. The 

 larva of Feltia ducens ( = subgothica) has been bred from egg to adult 

 and no character has been found b}^ which it may be distinguished from 

 the larva of Feltia jacuUfera. It seems probable that these quite 

 similar forms are not specifically distinct. The examination of a single 

 inflated larva of Euxoa tessellata has likewise revealed no character 

 by which this species may be distinguished from Euxoa messoria. 



In determining the character of the skin granules it should be borne 

 in mind that the coarse granules mentioned in the key are not more 

 than one-twentieth of a millimetre broad. A low power of the com- 

 pound microscope is essential for obtaining an adequate idea of their 

 appearance, although with a little practice the species can be deter- 

 mined readily with a good hand lens. 



