INSECTS. 



167 



distortions of the plant, especially obvious during the 

 flowering time, and for a short time afterwards. 

 The haulm withers, and shrivels at the point where 

 the larvae are present, i.e. above the lowest node, or 

 the lowest but one. 

 At the time when the 

 haulm begins to turn 

 yellow — ^that is, when 

 the grain begins to 

 ripen, — the larvae be- 

 come pupse; the haulm 

 now easily breaks off 

 at the infected spot ; 

 a strong winder heavy 

 rain throws it to the 

 ground. A badly in- 

 fested field looks, on 

 this account, as if a 

 herd of cattle had got 

 loose and trodden it 

 all down, or as if 

 the grain had been 

 devastated by hail. 

 Only a few haulms 

 bear ears containing 

 normally developed 

 grains. The flies 

 emerge from thepupte 

 in August and September, after which the females 

 quickly seek the winter corn, and lay their eggs 

 singly or in pairs on the leaves of the yet young 

 plants. The larvae creep between the leaf-sheath and 

 the still quite undeveloped haulm, and, in the case 

 of small haulms, a number of larvae may collect 

 together in the immediate neighbourhood of the 

 root, causing a spherical swelling. In many cases 

 the plant dies if its lower parts are inhabited by 

 many larvae. Before winter, the larvae attain their 



Fig. 111.— Plant of Barley, attacked by Hessiaa 

 Fly. The pupse at a. 



