278 INSECTS INFESTING WHEAT. 



dant in some localities and scarce in others. It cannot, there- 

 fore, truly be said to migrate from one part of a State to 

 another, or from one region to another." 



Again, writing of the probable limits of the Hessian fly, Dr. 

 Thomas says : " The question naturally arises whether this 

 pest will ever infest the wheat regions of western Dakota, 

 Montana, Utah, Colorado, and the Paciflc States and Territo- 

 ries? Wc believe (though not jiwarc that such a statement 

 may be hazarded) that it was originally an inhabitant of Cen- 

 tral and Southern Europe. It has become acclimated in the 

 Eastern, Atlantic, and Miildlc States, in the Valley of the 

 Upper St. Lawrence, and in the Valley of the Mississippi 

 River; that it can thrive in the elevated dry Rocky Mountain 

 plateau regions, and withstand the cool nights and rliy hot 

 atmosphere of the far west seems doubtful. At least, so 

 slowly has it spread westward, so slight an amount of wheat 

 or straw is transported westward (all produce of this kind 

 going eastward), that we doubt whether, during this century 

 at least, it will extend west of Kansas and Minnesota, where 

 it has already had a foothold for several years." 



From what has been said of the Hessian fly, it is obvious 

 that the wheat-growers of California cannot be too careful in 

 preventing the importation of this pest. 



Remediks. — Should this pest ai)pear in this State, a good 

 preventative of its spreading would be the use of No. 56 or 20. 



CHAPTER CLXXXIV. 



The Joint Worm. (Cal.) 



{Eanjloiaa tritici. — Fitch.) 



Order, Hymenopteka : Family, Chalcidid.e. 



[Living in galls or swellings on the lower part of wheat 

 plants; a footless pale yellow maggot. J 



The parent flies appear in the latter i)art of .\pril or Ix'gin- 

 ning of May, and pierce the stalk in nuincidus [(laces 

 imnu'diatelv above one of the joints, inserting an egg into 



