178 SHADE-TREES IN TOWNS AND CITIES 



collect in the crevices of the bark, and remain in a naked 

 state all winter. In the latter part of May, when they 

 change into the cocoon state, the presence of the pest is easily 

 detected. The cocoons are about one-sixteenth of an inch 

 long and perfectly white. On badly infested trees they 

 are piled one on top of the other in such large numbers 

 that the trunks look as if they had been whitewashed. 



In early June the insects emerge from their cocoons. 

 The females go up to the leaf and settle on the under side 

 along the veins. They grow in size and surround themselves 

 with a fluffy white mass and lay their eggs from which the 

 young larvae hatch. These scatter along the veins and suck 

 the sap from the leaves. They begin to migrate during the 

 latter part of July. They go along the petioles of the leaves, 

 the main limbs, and gather on the trunks where they form 

 their cocoons. During the latter part of July and early 

 August the cocoons of the newly hatched larvae begin to 

 appear on the trees. Toward the end of August they leave 

 the cocoons, pair, and then the females of the second brood 

 again lodge themselves on the under side of the leaves to lay 

 the eggs for the winter generation of larvae. It is at this 

 time that the infested sugar maples begin to lose their 

 leaves. 



Unlike other insects the several stages of metamorphosis 

 of this one are not completed within the same time. While 

 some of the insects are in cocoons others are already hatched 

 and still others are laying eggs on the under side of the 

 leaves. The additional fact that there are two broods a year 

 during the summer, produces conditions making it possible 

 to find the insect in all stages of development at any time in 

 midsummer. These peculiarities make the treatment of the 

 trees rather difficult, for the process that will destroy the 



