December, '21] parks: wheat sheath worm 491 



The injury was first described by Doane- in 191G, who observed seri- 

 ous damage to occur on the dr>' farms of Utah. The adult insect lays 

 several eggs in the leaf-sheath around the stem above the upper joint. 

 The larvae developing within cells in the sheath, cause a swelling and 

 hardening, which later results in the sheath above this point becom- 

 ing much enlarged. If the plant is well developed at egg-laying time, the 

 affected straw is short, and usually greatly distorted or bent at the upper 

 joint. If the plants are quite young at the time of oviposition, the head 

 is alwa}-s stunted, and is often unde\^eloped or unable to push its way 

 beyond the topmost leaf -sheath. Many straws do not get tall enough 

 to be cut by the reaper. This is especially true of wheat growing in 

 finishing furrows where growth has been retarded, and the straws are 

 more suitable for the work of the insect. An infestation of 20% may 

 mean a loss of one-fifth of the yield. The same infestation of H. tritici 

 will probably reduce the yield but little, unless lodging occurs. H. 

 tritici infested straws usually mature a satisfactory^ head. 



In Ohio the injury due to Harniolita vaginicolum has been severe 

 only in the northeastern counties. This includes ten counties east and 

 northeast of Lorain, Wayne, and Harrison. During 1918 severe loss 

 occured in this section to all wheat sowed after October 1st. vSpring 

 wheat suffered the worst. The injur\- decreased gradually until 1921, 

 when joint-worm, was at a low ebb all over the State. During this year 

 specimens of H. vaginicolum were taken along the Ohio River near the 

 southern point of the State and at points in southeastern counties. 



The surveyors did not obsen^e any specimens in western Ohio. It is 

 probably generally distributed over the eastern one-half of the State 

 and most abundant in the northeastern section. 



Date of sowing plats are m,aintained at most of the county experiment 

 farms for the purpose of determining the best wheat sowing date through 

 a series of years, and the effect of hessian fly upon wheat sowed at various 

 times. Two of these county experiment farms, namely, Tnmibull 

 County and Mahoning County, have had the date of sowing plat going 

 for five years. These counties are located in the section of the State 

 where H. vaginicolum is the dominating species. Each year of the 

 Wheat Insect Surve3^ except one, the writer has inspected these ])lats 

 to determine the presence of this species and the effect of time of sowing 

 upon its prevalence. In 1919, the data were collected by Mr. J. S. 

 Houser of the Ohio Experiment Station. Usually 200 straws were 

 examined and the percentage of infestation determined for the plat. 

 These are here given for the years 1918 — 1921. 



^Isosoma vaginicolum, Jour, nf Pkoii. Ent., Vol. 9, No. 5, pp. 398. 



