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these and other sorts of insects when their whole history is completely known. Then* 

 and then only, inasmuch as each species has its peculiar habits and ways of living? 

 can we propose rational means for their abatement. This is perfectly clear, as also that 

 experiments as to the means to be employed for the abatement of any one species are a 

 perfectly legitimate matter for Governmental expense. Still, the fact remains that we 

 can do but little, practically, to check the ravages of certain of our insect enemies. Many 

 appear suddenly and again disappear before remedies can be efficiently employed. For 

 the abating of many kinds we can only wait the action of their natural enemies. My 

 experience leads me to this one conclusion, that mechanical means for the abatement of any 

 insect injurious to vegetation are, as a rule and with some proper exceptions, preferable to the 

 employment of poisons. Before the American Association for the Advancement of Science, 

 in 1879, I read a paper showing that the damages resulting from the employment of Paris 

 Green and arsenical poisons outweighed the benefits, pecuniarily in the death of stock, 

 while accidents to persons had become not unfrequent from its unlicensed use. This protest 

 has, I believe, borne some fruit. I am also of opinion that more good would be brought 

 about by including an elementary course of entomology, teaching the life history of our 

 commoner and destructive insects, in the Public Schools, especially throughout the agri- 

 cultural districts, than by the present system of publishing reports which do not sufficiently 

 reach the farmers who pay for them. It should be the duty of the State Entomologists 

 to lecture in the Public Schools. If an easy text book were published, and an effort made 

 to have it introduced, good results would be soon obtained. Farmers' boys would learn 

 to destroy the nests of the tent caterpillar rather than of the robin. The protection of 

 birds and, in fact, all natural enemies of our predaceous insects is a main feature of the 

 whole matter. 



I may here refer to the Cotton Worm, Aletia argillacea. This species belongs to the 

 class of migratory pests. I have shown that it was probably introduced during the last 

 century from the West Indian Islands where cotton was cultivated. That, in common with 

 many other moths, it has a seasonal migration from south to north, and that its foothold 

 and multiplication on the soil of the United States was dependent on the introduction 

 and cultivation of the cotton plant. I was the first to show its full habits : that it hiber- 

 nated as a moth and that there was a geographical, climatic limit to its successful hiber- 

 nation. In other words, the moth, even within the cotton belt where I made my first 

 studies, did not survive the winter to lay fresh eggs on the young cotton of the ensuing 

 year, and that the new worms came from a fresh immigration of the moth from points 

 farther south. 



I can see no reason for any change in my general views on the whole matter of the 

 Cotton Worm. I could not, as a private individual, journey over the whole South and 

 find out the line of successful hibernation. That such a line exists somewhere is the 

 whole gist of my paper. Before I read it, it was not known that Aletia hibernated as a 

 moth, it was not known that it did not breed everywhere the ensuing year from eggs 

 laid by the progeny of the year before. The main question, so far as I can see, still 

 remains where I left it. 



The white Maple Spanner, Eudalimia subsignaria of Hubner, used to be so common 

 in Brooklyn and New York, from 1855 until well into the sixties, that the shade trees 

 of all kinds except the Ailanthus, became completely defoliated. I remember especially 

 one poor tree at the old Nassau Street post office in New York which became as bare as 

 in winter by the middle of June, and struggled with a stunted after-growth of leaves in 

 July. Everywhere the brown Measuring Worms used to hang down and cover the side- 

 walks in New York and suburbs to the great discomfort of the passers by. I have seen 

 ladies come into the house with as many as a dozen of the worms on their skirts or 

 looping over their dresses. The advent of the English sparrow changed all this ; the 

 naked brown larva? of the Maple Spanner disappeared before them and gradually all the 

 other naked larvje became scarce. Such were for instance the larvae of Eudryas, Alypia, 

 Thy reus Abbott ii, Deidamia inscripta, Everyx myron, Chamyris cerinthia, etc., all of 

 which I used to find abundant in the small gardens in Brooklyn, chiefly feeding on the 

 grapevines. The larva? of the Yapourer, Orgyia Leucostigma, being hairy and less palatable 

 to the sparrows, however, remained and multiplied ; becoming, in Philadelphia, as great 



