424 



AN ECONOMIC ENTOMOLOGY. 



into. A tree with rough bark, covered with moss, hchens or 

 other unnecessary growth, often harbors hundreds of specimens, 

 and one object of the farmer should be to destroy all hiding- 

 places that may be of service to the insects for winter-quarters. 

 Therefore, if possible, all fences should be whitewashed, as well 

 as all out-buildings. Insects do not like lime, and where a dozen 

 specimens may be found on a plain board fence, scarcely one 

 will venture on one that is limed. This kind of campaign is 

 especially effective against certain forms of plant-bugs, a large 

 proportion of which live through the winter in the half-grown or 

 adult condition. Offer them a bare soil wherever that is agricul- 

 turally feasible, and at all events never give them the opportunity 

 of hibernating in a weedy field — one that has been allowed to 

 grow up after harvest with the idea that it is to be turned under 

 in the spring. Such fields are veritable nurseries for insect pests. 



It frequently happens that a farmer is through with a crop 

 before the plants stop growing, and occasionally they remain in 

 the field weeks after they have ceased to be of any practical use. 

 During all this time the insects peculiar to that crop are multi- 

 plying, coming to maturity undisturbed, and providing for their 

 increase during the ensuing year. For instance, with cabbages : 

 if, after the heads are taken out, the butts and outer leaves are left 

 in the ground, the cabbage-lice will there increase and prepare 

 for the winter. If the butts are taken out and fed up, or destroyed 

 in any other satisfactory manner, it will put an immediate stop 

 to their development ; and if the practice is continued systemati- 

 cally, and cruciferous weeds are also kept down on the farm, 

 cabbage-lice will soon become so reduced in number as to be 

 practically harmless. So, from melon vines only a portion of 

 the crop is often gathered, and they are then left to grow and 

 decay naturally upon the ground. The vines may be infested by 

 borers, or they may harbor squash-bugs, or melon-lice, or a 

 number of other pests. By removing and destroying as soon as 

 there is no further use for them, a period is at once put to the 

 increase of these insects. They will be compelled to look else- 

 where for food or will starve to death. 



In corn-fields, leaving the roots and stumps in the ground 

 throughout the winter offers a premium for the increase of insects 

 that depredate upon this crop. Such pests as corn-worms" 



