130 THE PESTS OF THE FAKM. 



sails it gnaws a small hole nearly or quite through the hull, and 

 sometimes also through the chaffy covering of the grain, through 

 which it can make its escape easily when it becomes a winged moth. 

 The insects of the first, or summer brood, come to maturity in about 

 three weeks, remain but a short time in the chrysalis state, and 

 turn to winged moths in the autumn, and at this time may be 

 found, in the evening, in great numbers, laying their eggs on the 

 grain stored in barns and granaries. The moth-worms of the 

 second br<5bd remain in the grain through the winter, and do not 

 change to winged insects till the following summer, when they come 

 out, fly into the fields in the night, and lay their eggs on the young 

 ears of the growing grain. When damaged grain is sown it comes 

 up very thin ; the infected kernels never sprout, but the insects 

 lodged in them remain alive, finish their transformations in the field, 

 and in due time come out of the ground in the winged form. 



It has been proved by experience that the ravages of the two 

 kinds of grain-moths, whose history has been now given, can be 

 effectually checked by drying the damaged grain in .an oven or 

 kiln ; and that a heat of one hundred and sixty-seven degrees, by 

 Fahrenheit's thermometer, continued during twelve hours, will kill 

 the insects in all their forms. Indeed the heat may be reduced to 

 one hundred and four degrees, with the same effect, but the grain 

 must then be exposed to it for the space of two days. The other 

 means, that have been employed for the preservation of grain from 

 these destructive moths, it is unnecessary to describe ; they are 

 probably well known to most of our farmers and millers, and are 

 rarely so effectual as the process above mentioned. 



HESSIAN FLY. Under the name of DIPTERA, signifying two- 

 winged, are included all the insects that have only two wings, and 

 are provided with two little knobbed threads in the place of hind- 

 wings, and a mouth formed for sucking or lapping. Various kinds 

 of gnats and of .flies are therefore the insects belonging to this order. 

 The proboscis or sucker, wherewith they take their food, is placed 

 under the head, and sometimes can be drawn ap and concealed, 

 partly or wholly, within the cavity of the mouth. 



The young insects, hatched from the eggs of gnats and of flies, 

 are fleshy larvae, usually of a whitish color, and without legs. They 

 are commonly called maggots, and sometimes are mistaken foi 

 worms. They vary a good deal in their forms, structure, habits 

 and transformations, so that it is somewhat difficult to give an} 

 general description of them. Most insects are hatched from eggs 



