Insects in General 



Plowing 



Many insects pass certain tender stages of their development in 

 the ground or on plants in the fields. Plowing infested fields at the pro- 

 per time will do much toward destroying such insects. 



Late Planting 



Injury can sometimes be prevented by timing the planting of crops 

 so that they will not come up until danger of infestation is passed. 



Burning 



Many insects spend the winter in hibernation beneath the trash or 

 crop refuse on and about fields. If this waste matter, dead weeds and 

 grass about fence rows and ditch banks is burned during the fall or winter, 

 many insects will be destroyed which would otherwise damage crops the 

 following spring. 



Clean Culture 



Nearly all injurious insects fed upon wild plants before the land 

 was broken up and planted to crops. If weeds are allowed to grow in 

 a crop or about the fields, ditch banks, fences or roadsides, they attract 

 these insects to the vicinity. After the wild food plants have been 

 destroyed, the insects turn their attention to crops and much damage 

 results. Clean cultivation is always profitable from the standpoint of 

 insect control as well as for other reasons. 



Artificial Method of Control — Insecticides 



What substance to use and how to use it in artificial control depends 

 upon whether the insects are biting or sucking insects. There are 

 two general classes of insecticides, those which kill after they are eaten 

 (stomach poisons), and those which kill by coming in contact with the 

 insects (contact poisons). The first is used against insects which bite 

 their food, and the second against those which suck it. 



Control of Biting Insects 



In the control of most biting insects poisonous substances such as 

 Paris green and arsenate of lead are used. These are applied either as a 

 spray mixed with water or dry. In the latter case the poison is mixed 

 with low grade flour, air slaked lime or some other fine powder and dusted 

 onto the crop. The poisons "are often mixed with some substance which 

 the insects will eat, and this poisoned bait, as it is called, is scattered 

 over infested fields. 



In the control of some biting insects it is necessary to kill them while 

 in the egg stage. This is done by spraying with oils which can be mixed 

 with water or with lime-sulphur wash (See page 115). These oils are 

 petroleum products rendered soluble by the addition of vegetable oils 

 and are known by the trade name of "miscible oils." 



Many biting insects devour the entire leaf in feeding, while others 

 feed on the under side of the leaves only, eating all but the upper surface. 

 In applying stomach poisons it is very essential that the location of the 

 insects while feeding be known. If they feed on the under side of the 

 leaves the sprayer must be adjusted so that the poison is applied to the 

 lower surface. 



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