THE MEALY PLUM APHIS. 3 
SYNONYMS. 
1794. Aphis arundinis Fabricius, Ent. Syst., v. 4, p. 212. 
1794. Aphis pruni Fabricius, Ent. Syst., v. 4, p. 218. 
1886. Aphis phragmiticola Oestlund, List Aphid. Minn., p. 44. 
1911. Hyadaphis wnbellulariae Davidson, Jour. Econ. Ent., v. 4, p. 559. 
BICLOGY. 
THE EGG. 
Size 0.55 by 0.27 mm. The newly laid egg is pale green, covered with con- 
sSpicuous silvery filaments excreted by the oviparous female. It darkens rapidly 
and after about 5 days is shining black; the threads, however, remain silvery. — 
j2 
LOCATION ON TREES. 
The eggs are laid almost invariably in the axils of lateral buds of 
year-old or 2-year-old wood. Rarely more than three eggs are to be 
found to a single bud group. Occasionally eggs are placed in small 
sears or wrinkles in the bark of twigs. 
HATCHING. 
In 1916 hatching commenced about March 4, and continued for 
about two weeks. At this time most prune varieties were just starting 
to leaf, but the Myrobalans were in full leaf; nevertheless hatching 
was no earlier on the latter trees than on other plums and on apricots. 
THE STEM MOTHER. 
DESCRIPTION. 
Newly hatched.—Pale green; eyes dark red; antenne and legs pale gray; 
dorsum of head with a median longitudinal narrow pale green stripe; beak gray. 
Form oval. 
Antennz one-fourth the length of the body, 5-jointed. Comparative lengths: 
I, 0.03 mm.; II, 0.035; III, 0.045; IV, 0.05; V, 0.11 (0.060 plus 0.050); beak 
reaching to third abdominal segment, 0.21 mm. in length; cornicles minute 
raised pores. Style rounded. Length of body 0.63 mm.; width of body 0.39 
mm. 
During the first and second instars the color darkens and the dark markings 
on the head gradually disappear. The characteristic longitudinal stripes of 
darker green appear during the third and fourth instars. There are 3 of these, 
1 mediodorsal and 2 dorsolateral. The tarsi, apices of tibiz, cornicles, tip of 
beak, and distal third of the antenn of the growing nymph become gray. 
After the second molt the nymph assumes an elongate shape, and there 
appears on the sides and at the abdominal sutures a pruinose “ meal.’ This 
“meal” is much more scanty and less conspicuous in the stem mother than in 
later forms. 
Adult.—Yellowish-green with three longitudinal green stripes on dorsum; 
eyes dark red; antenngz pale green, distal joint dark gray; cornicles pale, dusky 
at apex; tarsi dark gray; style pale yellowish green; apex of beak blackish, 
Form elongate oval, comparatively flat; newly molted individuals carinate. 
