18 



pi ata no ides , A. pseudo-plat an us, and A. palmatum. They developed 

 gradually upon these trees, but died out in the course of the year, which 

 would seem to indicate that under ordinary circumstances the species 

 will not thrive on any of these maples. 



Habits and life history. — Occurring;, as this insect does, exclusively 

 upon the leaves of the maple during the summer time, it is necessary 

 for its existence that it should vary in its habits and life periods from 

 the species which we have just studied; in other words, there must be 

 a migration in the autumn from the leaves to the twigs before the leaves 

 fall, and there must be a return migration in the spring or early summer 

 from the twigs to the leaves. In the case of Pulvinaria innumerabilis, 

 only the one migration seems to be necessary, and that is only a partial 

 migration, namely, from the leaves to the twigs in the autumn. It is 

 only partial for the fact that many of the young settle and develop upon 

 young twigs of the present years growth. 



In his announcement of the validity of the Walsh-Kiley species in 



Fig. 12.— Pulvinaria accricola: a, larva of third stage— early hibernating l'miale— with tarsus and 

 antenna at right ; b, larva? of third stage on lower side of leaf, before migrating to twigs ; b, enlarged ; 

 fl, greatly enlarged, with tarsus and antenna still more enlarged (original). 



Bulletin Xo. 17, new series, of , this Division, the writer announced that 

 he had the species under daily observation at Washington, and expected 

 at an early date to publish its full life history. This statement was 

 made in August. 1898, and from that time down to October, 1899, the 

 species was under almost constant observation. Full notes on the life 

 history, including descriptions of the different stages, have been made 

 under the writers direction largely by Mr. T. Pergande. and also by 

 Mr. D. W. Coquillett, with occasional assistance from Mr. A. Busck ; and 

 from these notes and the writer's observations, the following summary 

 of the life history of the insect is drawn up : 



Eggs from specimens received from Knoxville, Tenn., began to hatch 

 the end of June, 1898. Eggs from specimens received from Dothan, 

 Ala., in 1899 began to hatch May 27. Eggs received from Knoxville, 

 Tenn., June 6, 1S99, were still unhatched. In Washington the secretion 

 of the egg sac and the depositing of eggs in the mass of wax and libers 



