j^ li-SBCT PESTS INCREASING OR JUST HARD,ER TO CONTROL? 



The answer to both questions is "Yes", i'kid we wis'i it vrere possible to stop 

 right there. But soiaeone always asks, "'vThy?", So here v/e go. 



Yes, insect pests., are increasing in two ways. First, there are nov; more 

 kinds of insects in the country vdiich do damage to crops. And secondly, there are, 

 at least in some years, more individuals of one kind or another to cause trouble. 



The first .tjtie of increase has resulted mainly from the accidental introdu.c- 

 tion of foreign species, I.iany of those introduced forms have not become pests, 

 but too often they have. And when they do become pests it is usually with a 

 vengeance since their natural checks, or enemies, have been left behind. In many 

 cases, also, these displaced insects find a far more abundant food supply in . 

 their adopted home. 



Then, too, there are native insects that have become pests as a result of 

 conditions being made more favorable for them. For example, the Codling Moth and 

 the Colorado Potato Beetle v;ere not pests previous to the planting of large 

 acreages of their favored food plants. This situation has allovred for the develop- 

 m.ent of pests of economic importance from some of our native species. Sometimes 

 rather simple changes in agricultural practices may bring about conditions which 

 ma!-:e a sorious problem out of an insect already there, but of no concern. For 

 exar.iple, in many of our orchards nowadays, v;e don't let the liogs eat the drops as 

 fast as they fall — nor do we have any substitute practice. 



Although very hard to prove, there is soino ovidcnce that certain spray or 

 dust materials may act in a way t!iat allows an otherwise unimportant insect or 

 related fonn, suddenly to become a dostru.ctiv3 pest. The interrelationship of the 

 use of DDT axid the appearance of the Two-spotted Llite in orchards may be one such 

 case. It is stated that in the State of V.'ashington the use of DDT has resulted in 

 the v/ooly aphid becoming a pest of major concern. 



And now for that second type of increasp — the greater numbers of individuals 

 of a certain species. 



Usually there is a fluctuation in the abundance of a species from season to 

 season, from orchard to orchard or from one scries of years as compared to another. 

 Although you maj'' not thinlc it tn.ie next July and August, the Japanese Beetle cannot 

 possibly be as numerous throughout tho infested area ne:rt summer because of -the 

 drought this past season. Eggs could not hatch nor young grubs become established 

 in nonnal numbers. 



On the other hand, tho dry, hot weather favored Apple Maggot, second brood 

 Codling Moth, Bud Moth, Aphids, and a host of others. They were more numerous or 

 will be next year if nothing interferes v;ith their development between now and 

 then, • 



Some insects beoomo more numerous according to a more or loss definite cycle. 

 Fall T/Tebtrorm and Tent Caterpillar ojid probably Red-banded Lcafroller are outstanding 

 examples of this. Extremely fa.vorable or adverse conditions, v/holly apart from the 

 normal factors governing the cycle, may on occasion cause tho variation frona the 

 usual pattern. 



Large acreages or block plantings of favored varieties or t;,TjOS of host plants 

 nearly always result in increased populations of certain species of insect posts 

 when other conditions are not unfavorable. 



