MASS. EXPERIMENT STATION BULLETIN 189. 



INTRODUCTION. 



Practically all insect pests of foreign origin found in the United States 

 have reached our seaports through the agency of commerce. The great 

 variety of living plants, as well as raw materials for use in manufacturing 

 enterprises and the miscellaneous freight and personal effects that are 

 daily received on our shores from all parts of the world, provide an ample 

 opportunity for the entrance of almost any destructive pest. Many of 

 these insect immigrants, on finding favorable climatic and food plant 

 conditions, become permanently established, and in the course of time 

 spread from their point of origin and become of more economic impor- 

 tance each year, unless checked by artificial agencies. 



The danger existing from these involuntary importations of destructive 

 insect pests is still further increased by the fact that in most instances 

 their natural enemies are not imported with them. Under these cir- 

 cumstances the pest is enabled to extend its activities without being 

 subject to the natural handicaps imposed by nature. This results in a 

 more rapid multiplication and a greater degree of destructiveness than 

 exists in the original habitat of the insect. 



Such, in brief, is the history of many of our most important and gen- 

 erally distributed insect pests of to-day. 



To the long list of foreign pests now found in the United States must 

 be added the European corn borer, or corn pyralid, Pyrausta nubilalis 

 Hiibner, which has recently become established in the eastern part of 

 Massachusetts. 



The caterpillar of this insect has long been recorded in Europe and 

 Asia as one of the most serious insect enemies of corn, hemp, millet, hops 

 and other crops. Corn and hop plants are very severely damaged by 

 this pest, 50 per cent of these crops often being destroyed in some sections 

 of Central Europe. 



As a result of studies made on the habits and destructive powers of the 

 European corn borer throughout the infested portion of Massachusetts 

 during the seasons of 1917 and 1918, it is evident that this species is 

 without doubt the most dangerous and destructive insect enemy of the 

 corn crop that has yet been introduced into the United States. As corn 

 is one of the bulwarks of American agriculture, and has within the past 

 few years become our most valuable crop from a monetary standpoint, 

 it ^^ill be recognized that the problem of controlling this insect which 

 threatens to destroy a large per cent of the crop each year is not con- 

 fined to Massachusetts, but is a problem of national importance, which 

 must be acted upon promptly and thoroughly to the end that the insect 

 may be at least confined to its present area of distribution, if ultimate 

 extermination is found to be impossible. 



If this insect is allowed to extend its area of distribution and reach 

 the corn belt of the middle western States, it will be a national calamity. 

 Although Massachusetts is universally considered to be a manufacturing 



