4 BULLETIN 774, U. S. DEPARTMENT OF AGRICULTURE. 
Antenne on very short frontal tubercles, barely one-third the length of the 
body, 5-jointed. Comparative lengths: I, 0.075 mm.; II, 0.06; III, 0.30; IV, 
0.14; V, 0.22 (0.08 plus 0.14). Beak, length 0.26 mm., reaching to second coxe; 
cornicles, 0.045 mm.; style, 0.17 mm. Cornicles wartlike, style ensiform. Pro- 
thorax and all abdominal segments bearing small, pale, lateral tubercles. Body 
bearing a sparse, inconspicuous clothing of granular “ meal,” most abundant at 
the sutures. Length of body (style included), 2.39 mm.; width of body, 1.06 mm. 
HABITS AND LENGTH OF NYMPHAL LIFE. 
After hatching, the young aphids seek out buds, often massing on 
those most advanced, and contrive to penetrate to the inner portions. 
On unopened buds they feed on the tender apical portions and num- 
bers of them die in such situations. Newly-hatched aphids move 
awkwardly on rough spiny leaf surfaces and frequently fail to make 
headway. This was observed especially in connection with Myroba- 
lan plum leaves, and perhaps explains the fact that the stem mothers 
on this tree have a high percentage of mortality in their early stages. 
After the blossoms shoot out the aphids feed on the petioles or on 
the outside of the sepals. In the leaf bud they feed generally on the 
under (outer) surface of the unfolding foliage and less abundantly 
on the reverse side. A favored point is that at the junction of sepal 
and petiole on the flower stalks. 
The first stem mothers matured on the plums at time of ful! bloom 
(March 19, in 1916), their growth being the more rapid on forward 
trees. On March 25 it was estimated that on the most advanced trees 
85 per cent of the aphids were mature, while on the most backward 
only 20 per cent were full grown. At this time the mature stem 
mothers were on the underside of the leaves; none were remaining on 
the fruit stalks. On March 28 virtually all stem mothers on forward 
trees were mature; on most backward trees 50 per cent were still im- 
mature. By April 5 no more immature stem mothers were found. 
Five stem mothers raised on potted Myrobalan seedlings developed 
in from 13 to 17 days. This time is perhaps less than in the average 
orchard, since the quality of food available for the newly-hatched 
aphid is often poor, while the seedlings were well in leaf at the time 
the experimental eggs hatched. It should be stated that the tempera- 
ture in 1916 during the first part of the development of the stem 
mother was higher than usual for that time of year. 
REPRODUCTION. 
The stem mothers deposit on an average about 4 young a day 
during a period of from 3 to 5 weeks. The rate of fecundity rises 
rapidly at first, maintains an even zenith for some three weeks, and 
then rapidly declines. Stem mothers may live for as long as three 
weeks after they have deposited their complement of young. 
