The "Cotton" Caterpillar - of Philadel-phians, which took the place of the measuring-worm on the trees of the public squares, after the introduction of the English sparrow, is the name given to the caterpillar produced by the Orgyia lucostigma, probably from the cottony cocoons which cover the rough bark of the tree trunks in the winter season. They ought to be easily destroyed by a hard brush. The cocoons are placed in the crevices of the rough bark for protection, and hence this rough bark makes a good trap for them.