18 LIFE HISTOEY OF THE ALDER BLIGHT APHIS. 



October 15^ 1908. — Examined some tall alders near Eosslyn, Va., 

 on which migrants from maples had settled in spring, and found 

 four colonies about 10 feet above the ground. These colonies were 

 from 6 to 10 inches long and contained apterous females and numer- 

 ous larva^ destined for hibernation. They were crawling down the 

 stems to the base, where they congregated in a dense mass, while a 

 great many were already in hiding between the fallen leaves near 

 the base of the trees. There were also many of the return migrants, 

 which were crawling to the tip of the branches or to the terminal 

 leaves, on which they settled, ready for migration. 



April 27^ 1909. — Examined again the above alders near Rosslyn 

 and found that some specimens of the hibernating series were already 

 in the second and third stages. 



In the youngest, or first stage the antennae are distinctly 4-jointed; 

 in the second stage, after eating a skin, they are 5-jointed; they are 

 also 5-jointed in the third stage, though the divisions between the 

 joints are much more distinct. 



Ju7ie 15, 1909. — Observed some migrants of Pemphigus acerifoUi 

 and their larvse on the underside of leaves of alders and numerous 

 colonies of such larvae on the stems or trunks of such shrubs from 

 1 to 10 feet above the ground, at Great Falls, Va. (Early in October 

 of the same year large colonies were seen on the same alders, about 

 4 to 15 feet above the ground, composed of apterous females, accom- 

 panied by numerous larvae of the hibernating series which were 

 swarming down the stems, and numbers of the return migrants.) 



June 29, 1910. — Saw again numbers of migrants of Pemphigus 

 acerifoUi, with recently deposited larvae near them, on the underside 

 of leaves of alder near Somerset, Md., while numbers of migrants 

 were still flying about. There were also numbers of colonies of 

 apterous females belonging to the hibernating series and numerous 

 larvae deposited by them. 



September 17, 1910. — Numerous colonies of Pemphigus tessellata, 

 about 4 feet above the ground, were again found on alders near 

 Somerset. They were composed of apterous females and their larvae, 

 besides pupae and return migrants. Many of these colonies were 

 being preyed upon by larvae of Feniseca tarquinius, as well by larvae 

 of coccinellid and chrysopid insects. Many of the apterous females 

 descended during October to the base of the shoots or stems, even as 

 far down as 1 or 2 inches below the surface, where they were sur- 

 rounded by numerous hiberating larvae, constituting a second series. 

 All of these colonies were covered with tunnels of clay constructed 

 by Cremastog aster lineolata Say. 



DESCRIPTION OF THE . PRINCIPAL STAGES OF PROCIPHILUS TES- 

 SELLATA FITCH. 



In view of the fact, as has already been stated, that the spring 

 migrants from the maple to the alder and the return fall migrants 

 from the alder to the maple are absolutely identical and, as a rule. 



