PLY, HESSIAN. 



seen. Much to his surprise they proved to be 

 minute, four-winged Ichneumon-flies, which 

 are parasitical, or prey, in the larva state, on 

 the bodies of other insects. He had hoped to 

 have obtained the true culprits, the cause of 

 the disease, supposing that the latter were al- 

 lied to the Hessian fly; but these little insects, 

 while in the larva state, had destroyed them 

 all, and, having finished their appointed task, 

 and undergone their transformations, now 

 made their escape from the straw in the 

 winged form. The scientific name, given to 

 this newly discovered parasite, was Eurytoma 

 Hordei, so called from Hordeum, the Latin 

 name for barley. It is very much like the 

 parasite (Eurytoma destructor) of the Hessian 

 fly, described by Mr. Say, but is rather larger, 

 of a jet black colour, except the legs, which 

 are blackish, with pale yellow joints. The head 

 and thorax are somewhat rough, and slightly 

 hairy ; the hind-body is smooth and polished. 

 The female is thirteen-hundredths of an inch 

 long; the male is rather smaller. It often 

 moves by little leaps, but the hindmost thighs 

 are not thickened. This minute insect is to 

 be reckoned among our friends, being ap- 

 pointed, by an all-wise and provident Creator, 

 to check the increase of the destructive fly 

 that attacks our barley. Though disappointed 

 in my attempts to obtain the latter, in its per- 

 fected state, I hail with pleasure the appear- 

 ance of its mortal enemy. " Although," says 

 Dr. Harris, " the barley-fly has not yet been 

 seen by me, there does not exist the smallest 

 doubt in my mind that it is a two-winged gnat, 

 like the Hessian fly and wheat-fly. Any one, 

 who will compare the history of the latter two 

 with what is known of the barley insect, will 

 arrive at the same conclusion. Both the Hes- 

 sian fly and the barley insect attack the culms 

 or straw of grain, which they injure to a great 

 extent; and both have a similar four-winged 

 parasite appropriated to them. It is probable 

 that the barley-fly is a species of Cecidomyia, 

 distinct from the Hessian and the wheat-flies." 



We have reason to believe, that the maggots 

 of the barley-fly remain in the straw during 

 the winter, and that they take the winged form 

 in the spring, in season to lay their eggs on 

 the young barley. It is therefore important to 

 prevent them from completing their transform- 

 ations. This may be done by burning the 

 stubble, which contains many of the insects, 

 in the autumn ; by destroying in the same way, 

 all the straw and refuse which is unfit for fod- 

 der; and by keeping the grain in close vessels 

 over one year, whereby the insects, which are 

 disclosed from the small heavy pieces of straw 

 remaining unwinnowed from the grain, will 

 perish without an opportunity to escape. 



FLY, HESSIAN. One of the most formida- 

 ble enemies of the wheat crop in the United 

 States, is the far-famed Hessian fly, a small 

 gnat or midge, which naturalists have placed in 

 the family of gall-gnats (Cecidomyiadce). The 

 insects of this family are very numerous, and 

 most of them in the maggot state live in galls, 

 or unnatural enlargements of the stems, leaves, 

 and buds of plants, caused by the punctures 

 of the winged insects in laying their eggs. 

 The following account of the Hessian fly, the 

 494 



FLY, HESSIAN. 



dread of farmers wherever wheat is cultivated 

 in North America, is chiefly taken from Har- 

 ris's Report on Destructive Insects, and Her- 

 rick's valuable paper upon this insect, pub- 

 lished in Silliman's American Journal of Science, 

 vol. 42. The brief history of the habits and 

 transformations of the Hessian fly will be 

 found to agree essentially with the excellent 

 observations on this insect, written in 1797, 

 by Dr. Isaac Chapman, and published in the 

 Memoirs of the Philadelphia Society for Promoting 

 Agriculture. 



"The head and thorax of this fly are black. 

 The hind-body is tawny, and covered with fine 

 grayish hairs. The wings are blackish, but 

 are more or less tinged with yellow at the base, 

 where also they are very narrow : they are 

 fringed with short hairs, and are rounded at 

 the end. The body measures about one- 

 tenth of an inch in length, and the wings 

 expand one-quarter of an inch, or more. 

 Two broods or generations are brought to 

 maturity in the course of a year, and the flies 

 appear in the spring and autumn, but rather 

 earlier in the Southern and Middle States than 

 in New England. The transformations of 

 some in each brood appear to be retarded be- 

 yond the usual time, as is found to be the case 

 with many other insects; so that the life of 

 these individuals, from the egg to the winged 

 state, extends to a year or more in length, 

 whereby the continuation of the species in 

 after years is made more sure. It has fre- 

 quently been asserted that the flies lay their 

 eggs on the grain in the ear ; but whether this 

 be true or not, it is certain that they do lay their 

 eggs on the young plants, and long before the 

 grain is ripe ; for many persons have witnessed 

 and testified to this fact. In the New England 

 States, winter wheat, as it is called, is usually 

 sown about the 1st of September. Towards 

 the end of this month, and in October, when 

 the grain has sprouted, and begins to show a 

 leaf or two, the flies appear in the fields, and, 

 having paired, begin to lay their eggs, in which 

 business they are occupied for several weeks. 

 The followinginte resting account of the manner 

 in which this is done, was written by Mr. Ed- 

 ward Tilghman, of Queen Ann county, Mary- 

 land, and was published in the eighth volume 

 of the Cultivator, in May, 1841. By the se- 

 cond week of October, the first sown wheat 

 being well up, and having generally put forth 

 its second and third blades, I resorted to my 

 field in a fine warm forenoon, to endeavour to 

 satisfy myself, by ocular demonstration, whe- 

 ther the fly did deposit the egg on the blades of 

 the growing plant. Selecting a favourable 

 spot to make my observation, I placed myself 

 in a reclining position in a furrow, and had 

 been on the watch but a minute or two, be- 

 fore I discovered a number of small black 

 flies alighting and sitting on the wheat plants 

 around me, and presently one settled on the 

 ridged surface of a blade of a plant completely 

 within my reach and distinct observation. She 

 immediately began depositing her eggs in the 

 longitudinal cavity between the little ridges of 

 the blade. I could distinctly see the eggs eject- 

 ed from a kind of tube or sting. After she 

 had deposited eight or ten eggs, I easily caught 



