1847.] hiseds Injurious to Vegetation. If 



arise from their coverts, sluggishly fly a few feet, and alight again. 

 In other fields, where none of the flax seeds could previously be 

 found, an occasional fly was met with, on the same day, A week 

 after this, on a thorough examination, no flies could be found, nor 

 were but two specimens afterwards met with, until the coming out 

 of the summer brood. 



Second Generation. 



After the full details that have already been given, but a few 

 words will be required under this head. About the first of May 

 the fly appears, and deposits its eggs upon the same crop of grain 

 that has already reared one brood, and also upon any spring 

 wheat that is sufficiently forward for its purposes. The radical 

 leaves of the winter wheat are now more or less Mithered, and 

 the fiy therefore selects the more luxuriant leaves that have put 

 forth above these. The worm hatches, and again makes its short 

 journey to its future home, at the base of the sheath; it conse- 

 quently now nestles at the first and second joints of the young 

 stalk, and is sometimes, though rarely, as high as the third joint. 

 Even before the worm reaches the base of the sheath, it has fre- 

 quently grown nearly to its full size (as shown, fig. w.) The 

 stalk has now attained such vigor and hardiness that it is seldom 

 destroyed by this spring attack. A slight swelling, immediately 

 above the joint, (fig. B. §§,) commonly indicates the presence of 

 the larva beneath. This is a fact which has been overlooked, or 

 at least not distinctly stated by writers hitherto. We only find it 

 noticed by Mr. Bergen, {CultivatGr, viii., 133,) who informs us 

 that in a crop of barley which was destioyed by the Hessian fly, 

 many of the stalks were " at the joints as thick as a man's fino-er." 

 The insect is therefore a true gall-^y, although when but one lar- 

 va succeeds in reaching the joint, the swelling caused by it is but 

 little if at all apparent. More commonly however, the straw be- 

 comes so weakened, that it is unable to sustain the weight of the 

 wheat head, and it accordingly bends down (as represented, fig. 

 B. ft,) with the force of the wind and rains. The appearance of 

 a badly infested field, as harvest time approaches, cannot better 

 be described than in the words of M. Kollar. The grain looks as 

 though a herd of cattle had passed through it, so broken and 

 tangled together is the straw. The worm attains its growth and 

 enters its flax seed state about the first of June, and the flies of 

 this second generation commonly come forth about the last of July 

 and in August. 



Miss Morris's theory. — Wc do not deem it necessary to go into 

 a detailed examination of the theory revived by Miss Morris in 

 1840, that the eggs of the Hessian fly are deposited in the grain, 

 and that the larva lies in the centre of the culm. We suppose 



