SB 

 818 

 C578 

 ENT 



^j^^^ D IV e INSECTS 



. 66, Revised Edition. Issued Septombor 21, 1908. 



ited States Department of Agriculture, 



BUREAU OF ENTOMOLOGY, 

 L. O. HOWARD, Entomologist and Chief of Bureau. 



THE JOINT- WORM. 



(hosnma tritici Fitch.) 



By F. M. Webster, 

 hi Charge of Cereal and Forage Plant Insect Investigations. 



Since the first known serious outbreak of the joint-worm (Isosoma 

 tritici Fitch) , which occurred in the wheat fields about Charlottesville 

 and Gordonsville, Va., during the years 1848 to 1854, this insect has 

 beenreported at irregular intervals and from widely separated localities. 

 While it is known to occur sparingly over most of the wheat-growing 

 sections of both the United States and Canada, and probably does 

 more damage than has generally been attributed to it, its reappear- 

 ance in the wheat fields of Indiana, Michigan, Ohio, Pennsylvania, 



Fig. \.— Isosoma tritici: Adult of the joint-worm. Much enlarged (from Howard). 



West Virginia, Virginia, Maryland, and Kansas in 1904, and in still 

 greater numbers in 1905, serves to bring it again to notice. In 1904 

 some fields of wheat in eastern Ohio were so badly damaged that they 

 were not harvested, and in 1905 a serious outbreak in northeastern 

 Indiana so discouraged some farmers that they questioned the advisa- 

 bility of putting in a crop of wheat at all. In southwestern Virginia 

 the pest was even more injurious in 1905 than it was the previous year. 

 The pest was also very destructive in western Ohio and eastern Indiana 

 during the spring of 1908. 

 52718— Cir. 66—08 



