WALNUT APHIDES IN CALIFORNIA. 
39 
orange-colored; cylindrical, long oval, slightly tapering to either end, 
four times as long as broad; deposited in compact masses of from 5 to 
25 on the leaf, usually on the underside, and with their long axis at 
right angles to the leaf surface; size, 1.3 by 0.35 mm. The larva: All 
black at hatching, later with pale markings, becoming more distinct 
after each successive molt. After the third molt the general color 
is dark purplish-black, with a median line of pale brick-red spots on 
the thorax and abdomen and also two lateral rows of similar spots. 
On segments 1 and 4 of the abdomen occur also two pale spots, one on 
either side of the median brick-colored spot and midway between it 
and the corresponding lateral spot. The full-grown larva has a 
length of 8 millimeters. The pupa: General color white, wing pads 
sienna brown. A large number of black spots and dashes are present 
but the prevailing color is white. Average size, 4 by 3.3 mm. The 
adult: Hemispherical, ashy-gray, with black markings, the elytra 
sometimes diffused with dull reddish blotches; head black, with 
central portion white or light gray; thorax (pronotum) black, with 
gray margins; elytra ashy-gray, with eight black spots on each 
elytron; legs yellow; abdomen reddish-yellow; average size, 5.2 by 
4.2 mm. The adults of this species, if confined without food, will 
devour one another. 
Table XIII indicates the predatory activities of two larvae of 
Adalia melanopleura on walnut plant lice. 
Table XIII. — Adalia melanopleura: Predatory activities on walnut plant lice, Walnut 
Creek, Cal, 1912. 
Num- 
Num- 
Num- 
Larva 
Date of 
Date of 
ber 
"lice" 
Date of 
ber 
"lice" 
Date of 
ber 
"lice" 
Date of 
Total 
"lice" 
eaten. 
Date of 
adult 
No. 
hatching. 
molt 1. 
eaten 
to 
molt 2. 
eaten, 
molts 
molt 3. 
eaten, 
molts 
tion. 
emer- 
gence. 
molt 1. 
lto2. 
2 to 3. 
1 
Sept. 17 
Sept. 20 
41 
Sept. 24 
38 
Sept. 26 
30 
Sept. 30 
181 
Oct. 12 
2 
17 
19 
35 
22 
34 
25 
33 
30 
194 
12 
In all, 375 plant lice were eaten in 26 days, or 14.4 per day per larva. 
The feeding period of both larvae was 13 days as contrasted with an 
average of practically 18 days for the larvae of the ashy-gray lady- 
bird. Adalia melanopleura is considerably smaller than that species, 
its larva consuming in a period of 13 days half as many plant lice 
as the larva of the larger species will devour in 18 days. This 
larger species will consume 70 larvae in a single day while the maggot 
of the large syrphid fly (Catabomba pyrastri) will dispose of over 100 
and during the 23 days or so of its existence will devour over 1,000, or 
about 43.5 lice per day. However, in contrasting the two groups of 
predaceous insects — Syrphidae and Coccinellidae — it must be remem- 
bered that the former are aphidophagous -only in the larval state 
