314 



Cmttfttrw of $atttral 



largements of the stems, leaves, and buds of 



Elants, caused by the punctures of the winged 

 isects in laying their eggs. The Hessian 

 fly, wheat-fly, arid some others differ from 

 the majority in not producing such altera- 

 tions in plants. The proboscis of these in- 

 sects is very short, and does not contain the 

 piercing bristles found in the long proboscis 

 of the biting gnats and mosquitoes. Their 

 antennae are long, composed of many little 

 bead-like joints, which are larger in the 

 males than in the females ; and each joint 

 is surrounded with short hairs. Their eyes 

 are kidney-shaped. Their legs are rather 

 long and very slender. Their wings have 

 only two, three, or four veins in them, and 

 are fringed with little hairs around the 

 edges ; when not in use, they are generally 

 carried flat on the back. The hind body of 

 the female often ends with a retractile, coni- 

 cal tube, wherewith they deposit their eggs. 

 Their young are little footless maggots, taper- 

 ing at each end, and generally of a deep yel- 

 low or orange colour. They live on the juices 

 of plants, and undergo their transformations 

 either in these plants or in the ground. 



The Hessian fly obtained its common name 

 from a supposition that it was imported into 

 England from Germany, and taken to North 

 America in some straw, by the Hessian 

 troops under the command of Sir W. Howe, 

 in the war of the Revolution. This sup- 

 position, however, has been thought to be 

 erroneous, because the early inquiries made 

 to discover the Hessian fly in Germany were 

 unsuccessful. Dr. Thaddeus Harris brings 

 together, with much industry, a large amount 

 of information from various sources relative 

 to its economy, its habits, and transforma- 

 tions ; and from his statement we shall en- 

 deavour to lay the principal facts before our 

 readers. The head and thorax of this fly are 

 black. The hind body is tawny, and co- 

 vered 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 gene- 

 rations are brought to maturity in the course 

 of a year, and the flies appear in the spring 

 and autumn. It has frequently been as- 

 serted that the flies lay their eggs on the 

 grains 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. The egg is about the fiftieth of an 

 inch long, and four thousandths of an inch 

 in diameter, cylindrical, translucent, and of 

 a pale red colour. The maggots, when they 

 first come out of the shells, are of a pale red 

 colour. Forthwith they crawl down the leaf, 

 and work their way between it and the main 

 stalk, passing downwards till they come to a 

 joint, just above which they remain, a little 

 below the surface of the ground, with the 

 head towards the root of the plant. Having 

 thus fixed themselves upon the stalk, they 

 become stationary, and never move from 

 the place till their transformations are com- 

 pleted. They do not eat the stalk, neither 



do they penetrate within it, as some persons 

 have supposed, but they lie lengthwise upon 

 its surface, covered by the lower part of the i 

 leaves, and are nourished wholly by the j 

 sap, which they appear to take by suction. 

 They soon lose their reddish colour, turn ! 

 pale, and will be found to be clouded with 

 whitish spots ; and through their transparent : 

 skins a greenish stripe may be seen in the ! 

 middle of their bodies. As they increase in 

 size, and grow plump arid firm, they become 

 , imbedded in the side of the stem, by the 

 i pressure of their bodies upon the growing 

 j plant ; but when two or three are fixed in 

 [ this manner around the stem, they weaken 

 j and impoverish the plant, and cause it to 

 fall down, or to wither and die. They usually 

 | come to their full size in five or six weeks, 

 and then measure about three-twentieths of 

 an inch in length. Their skin now gradually 

 hardens, becomes brownish, and soon changes 

 to a bright chestnut colour. This change j 

 usually happens about the first of December, j 

 when the insect may be said to enter on the | 

 pupa state, for after this time it takes no 

 more nourishment. The brown and leathery 

 skin, within which the maggot lias changed 

 to a pupa or chrysalis, is long, egg-shaped, 

 smooth, and marked with eleven transverse 

 lines, and measures one-eighth of an inch in 

 length. In this form it has been commonly 

 likened to a flax-seed. It appears, then, 

 from the remarks of the most careful ob- 

 servers that the maggots of the Hessian fly 

 do not cast off their skins in order to become 

 pupae, wherein they differ from the larv of ! 

 most other gnats, and agree with those of 

 common flies ; neither dp they spin cocoons, 

 as some of the Cecidomyians are supposed to 

 do. Inclosed within the dried skin of the 

 larva, wliich thus becomes a kind of cocoon 

 , or shell for the pupa, it jremains throughout , 

 i the winter, safely lodged in its bed on the side j 

 ' of the stem, near the root of the plant ; and 

 protected from the cold by the dead leaves. 



Very soon after the flies come forth in the 

 spring, they are prepared to lay their eggs 

 on the leaves of the wheat sown in the autumn ! 

 before, and also on the spring-sown wheat, i 

 that begins, at this time, to appear above | 

 the surface of the ground. They continue | 

 to come forth and lay their eggs for the ' 

 space of three weeks, after which they en- | 

 tirely disappear from the fields. The mag- 

 gots, hatched from these eggs, pass along 

 the stems of the wheat, nearly to the roots, I 

 become stationary, and turn to pupas in 

 June and July. In this state they are found 

 at the time of harvest, and, when the grain 

 is gathered, they remain in the stubble in the j 

 fields. To this there are, however, a few I 

 exceptions ; for a few of the insects do not j 

 pass so far down the side of the stems as to j 

 i be put of the way of the sickle when the 

 grain is reaped, and consequently will be 

 gathered and carried away with the straw ; 

 and from this circumstance it is possible that 

 they might have been imported in straw from 

 a foreign country. In the winged state, these 

 I flies, or more properly gnats, are very active, 

 I and, though very small and seemingly 

 feeble, are able to fly to a considerable dis- 

 | tance in search of fields of young grain. 



