76 ILLINOIS NATURAL HISTORY SURVEY CIRCULAR 47 



ABOUT INSECTICIDES 



Insect control sometimes is based on the division of insects 

 into two groups : those with chewing mouthparts and those with 

 sucking mouthparts. A stomach poison is usually prescribed for 

 those with chewing mouthparts, a contact poison for those with 

 sucking mouthparts. 



Lead arsenate is an example of a stomach poison and nicotine 

 sulfate an example of a contact poison. DDT and malathion may 

 act as either or both types of poison. This statement does not 

 mean that all insects can be controlled with DDT or malathion. 

 For example, while DDT is effective against a wide variety of 

 caterpillars, it does a poor job on bagworms. Unfortunately, 

 DDT kills many beneficial insects — those that prey on pests — 

 and thereby sometimes contributes to unusually heavy mite, 

 aphid, and scale infestations. 



Many insecticides are available to the person wishing to 

 control insect pests of trees and shrubs. The trend is toward a 

 specific insecticide for a specific pest. However, the number of 

 insecticides recommended in this circular has been kept as low as 

 possible, consistent with practical usage and effective results. 



The formulations recommended on pages 90-92 are for types 

 of sprayers shown in fig. 55-58 and the frontispiece. Formu- 

 lations for the mist blower, fig. 59, may require special con- 

 sideration. A general rule to follow in formulating for the mist 

 blower is to multiply by six the quantity of insecticide recom- 

 mended for the hydraulic sprayer. Insecticide solutions or emul- 

 sions are handled by mist blowers better than are wettable pow- 

 ders in suspension. However, wettable powders mixed with 

 water can be used in a mist blower with suitable nozzle adjust- 

 ment and adequate agitation in the tank. 



All insecticides should be handled as poisons. Some are more 

 poisonous to human beings than are others, and some are so haz- 

 ardous that they should be handled only by persons familiar with 

 them. The first step in handling all insecticides safely is to read 

 the label on the package, and the second is to follow the instruc- 

 tions given thereon. 



Although insecticide applications are depended upon for the 

 control of most insect pests of trees and shrubs, other measures 

 are sometimes used: syringing mite infestations on plants with 

 a strong stream of water ; picking and burning the overwintering 



