THE TIMOTHY STEM-BOKEK. 9 



PARASITIC ENEMIES. 



This insect is apparently a very attractive host. Three species 

 of parasitic Hymenoptera have been reared from it, all of them 

 new, representing three genera — two braconids and one a chalcidid. 



Messrs. H. L. Viereck a and J. C. Crawford 6 have kindly described 

 these parasites, giving them the following names: Heterospilus 

 mordellistenx Vier., Schizoprymnus phillipsi Vier., and Merisus 

 mordellistenx Crawf. The descriptions appear elsewhere over the 

 names of their respective authors. 



In May of this year, Mordellistena ustulata was found to be very 

 abundant at Wilmington, Ohio, in timothy; material was collected 

 and sent in to the laboratory at La Fayette, Ind., for rearing. Two 

 species of parasites were reared from it, Heterospilus mordellistenx 

 and Merisus mordellistenx. Schizoprymnus phillipsi and Heterospilus 

 mordellistenx were reared from material collected at Richmond, Ind., 

 in 1906 and 1908, respectively. The latter species and Merisus 

 mordellistenx were reared at La Fayette, Ind., in 1910. 



It is very probable that the parasitic enemies keep the beetles 

 pretty well in check and that this accounts for the appearance of 

 the beetles in small numbers only in any given locality. 



REMEDIAL MEASURES. 



As this insect has never appeared in destructive abundance, so far 

 as known, there has been no occasion to devise means of combating it. 

 If a serious outbreak should occur, however, a short crop rotation 

 should be adopted, allowing a field to remain in timothy sod not 

 more than two or three years, thus preventing this stem-borer from 

 becoming well established. The borders of the fields and waste places 

 should be mowed frequently during the months of June and July. 

 If this is done, the larvae will not be able to reach maturity. 



a Proceedings of the U. S. National Museum, vol. 39, pp. 401-408, 1911. 

 b Proceedings of the Entomological Society of Washington, vol. 12, no. 3, p. 145, 

 1910. 



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