habits of certain species of Eurytomides. 311 



interruption of the circulation of the sap, and in some 

 places the cultivation of barley was given up in con- 

 sequence thereof. When the barley is about eight or ten 

 inches high the effects of the disease begin to be visible 

 by a sudden cheek in the growth of the plants and the 

 yellow colour of the lower leaves. If the butts of the 

 straw are now examined the}^ will be found to be irre- 

 gularly swollen and discoloured between the second and 

 third joints, and instead of being hollow are rendered 

 solid, hard, and brittle, so that the stem above the 

 diseased part is impoverished and seldom produces any 

 grain. The worms are about one-tenth of an inch in 

 length and of a golden or straw-colour, and in the 

 month of November they appeared to have passed to the 

 chrysalis state, which extends through the winter. In 

 some cases the larva entered the pupa state early in the 

 spring, and the perfect insects began to make their 

 appearance on the 15th of June, escaping through 

 minute perforations in the straw which they gnawed for 

 this purpose. These larvae differ entirely from those of 

 Cccidomyia (which latter had been supposed by certain 

 writers to have been the real cause of the mischief) in 

 having the bodies softer and their skins more delicate 

 and tender, whilst the form of the head and structure of 

 the mouth are entirely unlike those of the Cecidomyian 

 larvae ; the head is round and partially retractile ; the 

 jaws are 'lateral and hooked, they meet at the points, and 

 are of a blackish colour, and apparently of a horny 

 texture, being distinctly visible even with a pocket micro- 

 scope ; hence it is evident that these larvae are liyme- 

 nopterous, " and are not the larvae of any dipterous 

 insect." The perfect insects thus obtained proved to 

 belong to the genus Eurytoma, and were described by 

 Dr. Harris in the ' New England Farmer ' for July 23rd, 

 1830 (vol. ix., p. 2), and in the first edition of his 

 ' Treatise 'as Eurytoma hordei. Eight years previously 

 seme of these insects, that came from a straw-bed in 

 Cambridge (Mass.), were shown to Dr. Harris. They 

 had proved very troublesome to children sleeping on the 

 bed, their bites or stings, being followed by considerable 

 irritation and inflammation, which lasted several days ; 

 so numerous were the insects that it was found necessary 

 to empty the bed-tick and burn the straw. 



In 1851 the ravages of the joint worm in the wheat 

 fields of Virginia attracted the attention of Dr. Fitch, 



