18 BULLETIN 100, U. S. DEPARTMENT OF AGRICULTURE. 
earliest egg deposition may be explained by the fact that until late 
in August males are quite scarce and so the females must wait on 
the leaves until the males are developed. Directly after mating the 
female repairs to the branches and limbs to deposit her eggs. Al- 
though eggs may be deposited anywhere along the limbs, and more 
rarely on the newer growth, the locations most preferred are the old 
scars of fallen leaves and the surface of the larger limbs near their 
bases. Another favored location is that in the crotches of the smaller 
limbs. Eggs are rarely laid along the stalk of the leaf or at the base 
of the leaflets, and if placed in those positions they fall to the ground 
when the leaf drops. Cavities and interstices in the bark are also 
chosen, but when infestation is very severe the eggs are laid in the 
open on the larger limbs (see PL II) . In such a case large groups of 
eggs are massed together by many females, but a single female lays not 
more than three or four in a group. The eggs are fastened together 
and to the plant surface by a thin, transparent, gluey substance. No 
accurate information was obtained as to the number of eggs a single 
aphis produced, but from general field observations together with 
dissections of gravid females the writer arrived at the conclusion that 
not more than 30 eggs fell to the share of each adult, and probably 
not over half that number. On July 20, 1911, five gravid females 
were dissected. These contained respectively 5, 3, 3, 4, and 4 well- 
developed ova, besides about a dozen much smaller ones. On August 
28, 1912, four oviparous females dissected contained respectively 
2, 2, 4, and 2 full-grown ova besides about 20 much smaller ones. All 
these individuals were taken on the leaves and had not oviposited. 
The largest eggs dissected were lozenge-shaped and measured 0.37 
mm. in length by 0.14 mm. in width. 
THE EGG (FIG. 1; PL. II). 
When first laid, the egg is pale lemon-yellow or whitish yellow, oval, 
almost twice as long as broad, natter than most eggs of Aphidida?, 
and slightly broader at the micropylar end. After two or three days 
it turns black and shines obscurely when placed under a strong light. 
The surface is beautifully sculptured with granular hexagonal mark- 
ings. These markings are thickened portions of the shell. The nar- 
row intermediate portions of the shell are extremely thin, so much so 
that four months after the egg has been laid the yellow interior sub- 
stance is plainly visible through them if subjected to a high power of 
magnification. It appears that about 85 per cent of the eggs are 
fertile. The average size is 0.50 mm. by 0.28 mm. The egg stage 
may be said to occupy, on the average, five months in California. 
