No. 6. 



Hessian Fly. 



203 



and which, in its perfect state, becomes, as 

 we are informed, a beetle of splendid colour- 

 ing, passes its larva-existence within the pith 

 of the plant. Additional examples, we be- 

 lieve, are not ditiicult to be obtained. 



To the directions given in the " Proceed- 

 ings" for avoiding the production of this per- 

 nicious insect, little seems necessary to be 

 added. We are inclined, however, earnestly 

 to repeat the recommendations of further 

 trial and observation. It would seem that 

 the farmer who uses seed-wheat from a dis- 

 trict ravaged by this animal, actually commits 

 the absurdity of planting Hessian Jlies for 

 the benefit of his next year's crop ! ! 



The precise period at which the minute 

 green worm escapes from the hollow of the 

 straw, to repose and undergo its subsequent 

 changes beneath the sheath of the leaf, is not 

 ascertained with accuracy ; and may furnish 

 a question for investigation. We are inform- 

 ed that Miss Morris is continuing her obser- 

 vations on growing wheat ; in which she will 

 probably ascertain the fact. It is in the pow- 

 er of our readers to confirm or reject her 

 conclusions, both in this and in what she re- 

 gards as already established. 



With a view to illustrate more fully this 

 interesting and important subject, for the 

 benefit of those who have not studied the 

 branch of natural history to which it belongs, 

 we have determined to offer, 1. an explana- 

 tion of the meaning of the words larva, pupa, 

 and perfect insect ; 2. an account of the Hes- 

 sian fly as an object of science ; and 3. a de- 

 scription of the Ceraphron, a parasitic insect, 

 in reality its enemy, but which is frequently 

 mistaken for it. The two last articles will 

 be compiled from the writings of Say. 



1. All insects, at different periods of their 

 lives, shed their skins or shells. Some of 

 them, as spiders, centipedes, &c. do not very 

 materially change their form in consequence ; 

 others, as grasshoppers, acquire wings ; while 

 vast numbers change their appearance so en- 

 tirely as to render it incredible, without ocu- 

 lar evidence, that they were the same ani- 

 mals. Among all these, the class of " true or 

 proper insects," enormous both by the number 

 of individuals which belong to it, and by the 

 number of species under which they have to 

 be classed, assume three successive forms, to 

 which are given the names which we have 

 above recited. 



The most convenient and familiar instances 

 of these are drawn from butterflies, moths, 

 and other flies. In these, the insect in its 

 first stage, called, as we have above said, the 

 larva, goes generally by the name of a worm, 

 maggot or caterpillar. Examples of these 

 are sufficiently common. Such are caterpil- 



lars, and bee and wasp worms. The white 

 substances called " ants' eggs," but larger 

 than the ants themselves, which these ani- 

 mals carry away so eagerly when their nests 

 are opened, are larvas which afterwards pro- 

 duce beings like their parents; and are fed 

 with great care by their purveyors. Larvas 

 of some kinds greatly resemble the fully de- 

 veloped insect ; as grasshoppers. It is obvious 

 that no one of the words " worm," " maggot," 

 "caterpillar," &c. would be applicable to all 

 of these ; and as they are all analogous, a 

 word was necessary to express them. For 

 this the term larva was adopted ; meaning a 

 mask ; because the visible shell of the insect 

 in this state concealed the forms which were 

 to be displayed after casting it off. Larvce 

 is the Latin plural. In general, the larva 

 seems to have little business in the world but 

 to feed and grow. 



In the second stage of their existence, in- 

 sects can be found, on dissecting them with 

 needles, to possess the wings and other parta 

 which they are to employ in their subsequent 

 condition. These, however, are tender, and 

 at first imperfect, requiring time to become 

 fitted for use. For this purpose many of 

 them, including, we believe, the whole tribe 

 of flies, remain for some time in a state re- 

 sembling sleep; and when disturbed, rarely 

 exhibit more motion than a momentary wrig- 

 gling. They are encased in flat rings of 

 shell, generally harder than the skin of the 

 larva ; and often of brilliant and showy co- 

 lours. They are found sometimes naked, in 

 sheltered situations ; but in many kinds co- 

 vered with a web, and adhering to trees, 

 walls, rocks, &c. Of this kind are the mass- 

 es like pods of plants, seen hanging all win- 

 ter to the branches of trees. The inside of 

 these casings are webs ; and the outside a 

 collection of pieces of leaves, bark and sticks. 

 Other insects in the second stage, differ but 

 little in their appearance from the first and 

 third stages ; and others differ in their forms 

 and mode of life to the most amazing extent. 

 Thus, if the writer of these notes apprehend 

 correctly, it is in the first stage that the seven- 

 teen-years locust lives under ground, covered 

 with a hard horny shell, and provided with 

 strong arms for digging. Its second stage 

 seems to be a mere short interval of repose, 

 prior to its final change to the winged form. 



To express beings so unlike, and yet iden- 

 tical in their analogy, the word "pw^a" is 

 now generally used. Its original meaning 

 is 'a child in swaddling clothes;' which idea 

 agrees very well with the pupas of flies, as 

 we have been describing them. Pupce is the 

 Latin plural. They have sometimes been 

 called " chrysalises," " chrysalids," or in La- 

 tin and Greek, " chrysalides;" terms now less 

 in use than formerly. " Chrysalis," anciently 



