SEVENTH ANNUAL YEAR BOOK-PART X. 653 



moth and the Mexican holl weevil. Destructive as these insects have 

 been, they also produced some beneficial results. The San Jose scale 

 has given us state entomologists and much needed crop pest laws; in 

 lead arsenate the Gypsy moth has hastened the perfection of an arsenical 

 spray, harmless to the most sensitive plants; the Mexican cotton boll wee- 

 vil, even though it caused the loss of $20,000,000 last year, ultimately prom- 

 ises to repay it to the south by awakening the cotton growers to the 

 importance of better general cultural methods — methods now necessary 

 in order to raise cotton at all. Before considering the specific insects 

 which infest various crops here, perhaps the remedies for them should 

 be discussed in a general way. Remedies may be classified into three 

 more or less distinct classes — natural or biological, cultural and direct 

 or artificial. Natural or bioligical remedies are the most important and 

 the most permanent. They seek to restore the equilibrium which has 

 been destroyed. Examples of such remedies are to be found in the 

 various parasitic insects imported to prey upon the San Jose scale, 

 cotton boll weevil, and other imported insects which thrive so well here 

 because of the absence of their natural parasites. Often for some un- 

 known reason these parasites will not thrive under the new conditions, 

 as was the case with the kelep ant from which so much was expected 

 in the south. In time nature herself restores the equilibrium. While 

 the kelep ant has failed to check the cotton boll weevil it is now noticed 

 that some of the native ants are beginning to prey upon it, so that ulti- 

 mately they may effectually check it. For some insects, birds and 

 fungus diseases are most important. The spread of diseases can be 

 aided very little, but it is within the power of everyone to protect and 

 encourage the birds. Cultural remedies are often cheapest and most 

 efficient. For field crops, except in rare cases, they are the only reme- 

 dies practicable for the farmer to use. They often consist of plowing or 

 cultivating the ground at a time most detrimental to the insects, of 

 clearing away rubbish and remains of infested plants, and of growing 

 varieties which are more or less immune from injury. Direct or artificial 

 remedies are those in which we most commonly seek relief when we find 

 an insect infesting our crops. They are really least important in the 

 end for they give but temporary relief. They consist chiefly of poison- 

 ing, and picking and trapping with trap crops or piles of straw or other 

 material which may be destroyed. There are two general classes of poisons 

 employed, internal and external, or contact poisons. The former are 

 used for all insects which feed where they are accessible and have bit- 

 ing mouth parts such as caterpillars, beetles, etc. These external poisons 

 are usually some of the arsenicals, that is, chemicals which contain 

 arsenic in some compound, as the arsenates and arsenites, lear arsenate, 

 lime arsenite, paris green, etc. Care must be taken with the most of 

 them that the plant is not injured. Many of the cultivated plants are 

 very sensitive to soluble arsenicals. Lead arsenate is much the least 

 soluble of the arsenicals, and therefore the least injurious to plants with 

 delicate foliage. Paris green, Scheele's green, and London purple are 

 cheaper but variable in composition and somewhat soluble. Paris green 

 should be used with twice its weight of lime to lessen the injury. Lime 

 and soda arsenites are constant, but also soluble enough to be unsafe 



