1908.] PUBLIC DOCUMENT No. 73. 223 



I was also impressed by the effective work being done by federal 

 and State authorities to prevent the spread of these pests on 

 vehicles passing along the main travelled roads outside the residential 

 districts. The thorough cutting out of underbrush, and the thinning, 

 pruning, banding and spraying of the trees on both sides of these roads 

 for many miles, will do much to prevent the carrying of the caterpillars 

 into new territory. The truly astonishing and very gratifying results 

 which are thus being accomplished throughout the residential districts 

 and along the main highways against these pests show wise legislation, 

 and very efficient work by those employed to administer it. 



A proposition to exterminate the gypsy and brown-tail moths with 

 their natural enemies for the paltry sum of $25,000 is certainly very 

 alluring. It is not surprising that sincere, thoughtful men should be 

 caught with such a bait, and led to use their money and influence to 

 investigate the proposition and its author, and to try to induce the 

 State authorities to invest in such a cheap and alluring " cure-all." I 

 talked with some of those to whom this proposition appeals very 

 strongly, and I have carefully read the report of the lawyer sent to 

 California to investigate the matter. I failed to get from these sources 

 any convincing arguments or information which would appeal to a true 

 scientist who is at all conversant with insect problems. The control of 

 the gypsy and brown -tail moths presents a problem which is scientific 

 in all of its aspects, and one which demands thorough knowledge of in- 

 sects, their lives, their habits, their inter-relations, their enemies, and 

 man's methods for checking their ravages. In brief, it is an entomo- 

 logical problem, to be worked out by entomologists trained along eco- 

 nomic lines. This is especially true in the effort now being made to 

 fight these pests with their natural enemies. 



It is well known that many insect pests are held in check in their 

 native countries by their natural enemies, so that their periods of 

 destructiveness come at longer or shorter intervals, but never entirely 

 cease. And we know from sad experience in America that insect pests 

 introduced from other countries may be more destructive here than in 

 their native home, due largely perhaps to the absence of their natural 

 native checks, which may be other insects or different climatic or en- 

 vironmental conditions. It is an alluring thought that if we could only 

 bring their native enemies here and get them at work the problem of 

 the control of these pests would be accomplished. This is much more 

 easily said than done, but much work has been and is being done along 

 this line in various parts of the world. But as yet no "science of 

 parasitology " for insects has been developed, and if there ever is, its 

 successful practitioners must be entomologists in the broadest sense of 

 the term, and not horticulturists or pseudo-scientists. 



All insect pests are not alike in their inter-relations with local con- 

 ditions and natural enemies, so that the successful control of one pest 

 by the introduction of its enemies is not a guarantee that another insect 

 with very different habits may be similarly controlled. The striking 



