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The Wheat-Straw Worm, 



( Tsosoma tritici Riley. ) 



So much is heard of the Hessian Fly in Kansas that injuries 

 to the wheat by other similarly working pests are likely to be 

 attributed to the Fly. Among these other injurious wheat 

 insects the Wheat-straw Worm {Isosoma tritici) is not the least 

 important. 



Last year the presence of this wheat pest was reported to us 

 from about one-fourth of the counties of the state, the insect 

 being especially prevalent in Central and Western Kansas. 

 Some information concerning the pest was given from our labor- 

 atory to the state newspaper press during the summer. The 

 object of the present bulletin is to call attention again to the 

 presence of this pest and to suggest certain available remedies. 



The Wheat-straw Worm has been recognized as an insect 

 injurious to wheat only since 1880, but observations by various 

 investigators, notably, Dr. C. V. Riley, Mr. F. M. Webster and 

 Prof. S. A. Forbes, have pretty fully revealed its life history. 

 The insect belongs to the family Chalcidida of the order Hymen- 

 optera, and is of the same genus, Isosoma, as the Joint Worm, 

 which also infests wheat. The Chalcids are minute four-winged 

 flies, mostly parasitic upon other insects. A few, however, as 

 the Isosomas, are plant-eating, and themselves suffer from the 

 attacks of the parasitic species of their own family. 



The life history of this pest is. briefly, as follows : In March 

 and April adults issue from the last year's wheat-straws, either in 

 stubble or volunteer or in the stack, and lay their eggs on the 

 tender leaves of the growing wheat. The larvae, on hatching, 

 burrow into the stem, pupate, and soon mature, the adults 

 emerging in the latter part of May and early part of June. These 

 adults lay their eggs in the now maturing wheat, and another 

 brood of destructive larvae hatches. These larvae pupate in 

 the straws either in stubble or stack before winter, and pass the 

 winter in the pupal stage. The following spring the adults 



