SHALL WE PAY OUR DEBT? 363 



the right time to clean up the young caterpillars as 

 they emerge from the eggs of moths and butter- 

 flies. How many they take in a season, there is no 

 way to estimate. They also eat bark lice, scale 

 insects, bark and boring beetles. They help the 

 orchard orioles with the click beetles, while they 

 are fond of weevils, ants, cadis flies, May flies, 

 spiders and snails. 



There can be no question concerning the value 

 of the work of warblers in tree and vegetable con- 

 servation. While working with dozens of the big 

 night moths of June, securing data for a book, 

 "Moths of the Limberlost," I have had the females 

 of some of the commonest species, Cecropia and 

 Polyphemus, lay by actual count from three to seven 

 hundred eggs each, while Luna and Regalis would 

 average from three to five hundred. Placed in 

 freedom, these eggs would have covered the under- 

 sides of leaves of orchard and ornamental trees and 

 of hickory and walnut, among the most valuable 

 forest trees, with millions of caterpillars, which, 

 unchecked by the birds, at maturity would be 

 worms measuring from four to six inches in length., 

 each consuming his weight in leaves in a day. 

 Were it not for the work of warblers, in spite of 

 any form of burning or spraying, so many of these 

 eggs would escape on the undersides of leaves that 

 in a few years' time our orchard, field, and forest 

 trees would be denuded of leaves by midsummer. 

 Then the hot sun shining on the bare branches 



