140 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 10 



the Rocky Mountains, and a large amount of material was reared from 

 these collections. From data thus secured it became evident that in 

 order to establish definitely the identity and economic status of a 

 species a large amount of careful and accurate breeding under control 

 conditions would be necessary. Little was accomplished along these 

 lines until 1912, since which time the writer has secured a large amount 

 of valuable data on this most interesting and difficult group. These 

 observations throw a flood of light on the economic importance of the 

 Isosoma or joint worms, and clearly indicate that I. tritici is one of the 

 most important pests of wheat in the Eastern States. The average 

 farmer often confuses it with the Hessian fly, since the writer has had 

 farmers tell him repeatedly that Hessian fly was injuring their wheat 

 and upon examination it proved to be /. tritici. If wheat is badly 

 straw-fallen before harvest, the farmer usually attributes the damage 

 to the fly without examination. 



Successful breeding of the many species of Isosoma in confinement 

 is accomplished only under the most trying diflaculties. A number of 

 different types of cages have been tried, with varying degrees of suc- 

 cess. There are two cages that have given fairly good results, though 

 they are by no means perfect. One (PI. 8, figs. 1, 2 and 4) consists 

 of a wooden frame 3 feet square by 4 feet tall, two sides of which con- 

 sist of a stout sash fitted with four large panes of glass. One of these 

 sides is a hinged door the full size of the sash. The three other sides 

 are covered with the best grade of theese-cloth on the inside and 

 |-inch mesh galvanized iron wire on the outside, to prevent the cloth 

 being torn. The other cage (PI. 8, fig. 3) consists of glass cylinders 

 9 X 15 inches and 11 x 24 inches, respectively, with cheese-cloth cover 

 over the top. Plants are potted in 10-inch and 12-inch flower pots 

 and the cylinders placed over them. These cylinder cages should-be 

 shaded. 



One of the greatest difficulties in breeding Isosoma arises from the 

 fact that the plants must mature, and it seems very difficult to provide 

 normal growing conditions for the plant and, at the same time, confine 

 these tiny insects. Aphids also greatly complicate the situation and in 

 spite of the utmost care some will gain entrance and in a short time 

 threaten the life of the plants. Furthermore, the Isosoma are con- 

 stantly disturbed by the aphids and do not succeed in ovipositing. 

 With two exceptions the different species have but one generation a 

 year, therefore, should misforttme overtake some of the cages, a whole 

 year is lost. 



There are eighteen species of Isosoma occurring east of the Missis- 

 sippi river, seventeen of which the writer has reared in confinement 

 from adult to adult, and has thus learned some of the main facts 



