DIPTERA. 433 



when it lays its own eggs, four or five together, in a single egg of 

 the Hessian fly. This, it appears, does not prevent the latter 

 from hatching, but the maggot of the Hessian fly is unable to go 

 through its transformation, and dies after taking the flax-seed 

 form. Meanwhile its intestine foes are hatched, come to their 

 growth, spin themselves little brownish cocoons within the skin 

 of their victim, and, in due time, are changed to winged insects, 

 and eat their way out. Such are some of the natural means, 

 provided by a benevolent Providence, to check the ravages of 

 the destructive Hessian fly. If we are humiliated by the reflec- 

 tion, that the Author of the universe should have made even small 

 and feeble insects the instruments of His power, and that He 

 should occasionally permit them to become the scourges of our 

 race, ought we not to admire His wisdom in the formation of 

 the still more humble agents that are appointed to arrest the work 

 of destruction. 



In the years 1829 and 1830 several communications were pub- 

 lished in the eighth volume of Fessenden's " New England Far- 

 mer," * respecting a disease of bailey straw, produced by the 

 punctures of insects. The first account of this disease, that has 

 fallen under my notice, is contained in an extract from a letter, 

 dated August 1 6th, 1829, from the Honorable John Merrill, of 

 Newburyport, to Mr. Fessenden ; wherein it is stated, that the 

 barley, in the neighbourhood of iSewburyport, yielded only a 

 very small crop ; on some farms not much more than the seed 

 sown. Most of the stalks were found to have a number of small 

 worms within them, near to the second joint, and had become 

 hardened in the part attacked, from the interruption of the cir- 

 culation of the sap. During several years previous to this date, 

 the barley crops, in various parts of Essex and Middlesex coun- 

 ties, were more or less injured in the same way ; and, in some 

 places, the cultivation of this grain was given up in conse- 

 quence thereof. It was supposed that the insects, producing 

 this disease, were imported from Bremen, or some other port in 

 the north of Europe, in some barley that was sown in the vicinity 

 of Newbury, three or four years before 1829. f The worms or 



* Pages 43, 138, 217, 299, 330, and 402. Also Vol. IX., p. 2, and Vol. X., p. 11. 

 f " New England Farmer," Vol. VIII., p. 217. 



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