YALE AGRICULTURAL LECTURES. 29 



Hessian fly with us is now kept in subjection by its parasite. 

 And Dr. Fitch thinks the reason why the midge is so vastly 

 more numerous and destructive here than it ever has been 

 in Europe is, because this parasitic destroyer, its inveterate 

 enemy, has never reached our country. Thus we have received 

 the evil without the remedy. There are two ways by which 

 it is in our power to abate this evil ; by destroying, 1st, the 

 fly itsel ; and 2d, its larva. If, early in June, in the evening, 

 when the flies in a swarm are dancing about the wheat heads 

 to deposit their eggs therein, the field be swept over with a 

 suitable kind of net, the flies may be captured therein, and 

 destroyed in such multitudes that the few that are missed will 

 be able to do little injury to the crop. Of the larvae, a portion 

 remain in the wheat heads at harvest, and are taken into the 

 barn, and are finally gathered among the screenings of the fan 

 ning mill, which should be burned, or fed to poultry, and not 

 thrown out, as they usually are, among the litter of the barn 

 yard, where they mature and hatch another swarm of flies. 

 The other portion of these larvae have at harvest descended to 

 the ground, where they repose slightly under the surface till 

 they hatch into flies the following May ; and it has been thought 

 that by plowing the wheat stubble they would be buried so 

 deep as to smother them ; but experiments are needed, to 

 demonstrate whether this idea is well founded these Iarva3 

 being very tenacious of life. Water will not drown them. Dr. 

 Fitch has kept them submerged in vials of water three months, 

 and then on placing them on paper they begin to wriggle and 

 crawl away. 



The audience being invited to ask questions on the subject 

 of the lecture, if so disposed, availed themselves of the permis 

 sion. Dr. Fitch, in answer to sundry queries, said that neither 

 sowing lime on wheat when the dew was on, nor sowing salt, 

 nor using sulphur or salt in the granary, nor tobacco-water 

 sprinkled on the field, were specifics. Donald G. Mitchell 

 suggested, as it was uncertain whether deep plowing would 



