64 



ean tell almost to a year) the age of a colony. We found that the terri- 

 tory over which they were spread was a large one and that it would be 

 a year or more after the present work was begun before we would be 

 able to locate the outer colonies. We do not say a whole town is infested ; 

 we can only say the insect occurs in that town. So long as they are 

 left the colonies Avill be spreading until the whole town will become 

 thoroughly and fully infested. The territory infested is about 200 

 square miles, including thirty towns and cities. A j)art of that terri- 

 tory we think has been cleared. Colonies which were known to exist 

 in certain places three years ago show no trace of the insect. There- 

 fore we think we have reason to believe that these colonies are really 

 exterminated 5 but I doubt if I should want to say they are extermi- 

 nated until we have watched them ten years. 



We have been giving especial attention this year to the food plants, 

 and have a list of over three hundred plants that this insect feeds on 

 in Massachusetts, some not natives of this country. Some cotton 

 plants were brought from the South, and we find that it is a very 

 excellent food plant for them. They revel in it; in fact, they ate the 

 whole thing up. If they should get into the South I think they would 

 be capable of committing sad havoc there. 



Our field director is an ornithologist, and he has been giving a great 

 deal of time to the subject of birds. He has been working it out very 

 carefully, and has much he could say if it were so desired. 



We have been giving a great deal of attention to i)redaceous insects 

 with a view of breeding predaceous beetles. We have some eight or 

 ten of these, and they are certainly doing good work. Every report on 

 entomology that you take up contains a list of predaceous insects. 

 We have some that are not given in these reports. We have about 

 thirteen species of true parasitic insects. 1 sent the Diptera to Dr, 

 Williston for determination, and after giving them a preliminary exam- 

 ination he told me there were so many species of this genus and so many 

 of that which were probably new. 



Parasitic plants is a subject we took up. I talked over the matter 

 with Dr. Thaxter and Dr. Farlow, but they gave us no encouragement 

 in regard to the matter. Dr. Thaxter said, "Why don't you use Paris 

 green!" We gave him our exj)erience with this insect — that it would 

 eat more Paris green than the foliage of the trees could bear and still 

 transform and lay its eggs, which would give rise to caterpillars the 

 next year. I did not believe it at first, and I doubt if any of you would 

 have accepted it. I took some of the insects home and fed a large num- 

 ber of them, and I could not believe my own results and had my assist- 

 ants try it again. I had it tried in the field, and I tried it three years 

 in succession myself, and I am obliged to say that you can not kill this 

 insect with Paris green unless you use more than it is possible to put 

 on the trees without destroying the foliage. 



As the females do not fly, of course the distribution in the adult stage 

 is very limited. But the caterpillars in the early stages spin down 



