103 
given is of this Aphis, and not of Siphonophora fragarie. In the 
absence of specimens of the winged forms, I have not ventured to 
give a name to this species, especially as I am in doubt whether it 
should be regarded as a root form, properly so-called, or whether it 
is an aérial plant-louse, which had simply resorted to the crown at 
that season for protection and reproduction.* 
I here describe and figure this form, merely for the purpose of 
subsequent identification. 
This is a short ‘ovate plant-louse, with short five-jointed+ anten- 
ne, not on tubercles; a thick, prominent tail, and straight, cylin- 
drical, slightly tapering honey-tubes. 
The general color is a dark, bluish green. The basal joints of 
the antenne, the legs, the honey-tubes, and the tail, are yellow; the 
head yellow or green. The tips of the honey-tubes, the tarsi, the 
tibio-femoral articulations, and the distal joints of the antenneze are 
dark. Young specimens are pale green throughout. 
The body of an adult is about .1 mm. in length, by three-fourths 
as wide. The honey-tubes measure .2 mm., the tail .1 mm., and 
the antenne .8 mm. The third joint of the antenne is about twice 
as long as the fourth, the basal part of the fifth being a little 
shorter than the latter, and its filament about three times as long. 
NATURAL ENEMIES. 
All the plant-lice agree in being peculiarly susceptible to attack 
by a variety of enemies,—minute parasitic Hymenoptera, chiefly of 
the genus Aphidius, the larve of Syrphus flies, and many species 
of lady-bugs (Coccinellide), both in the adult and larval stages. 
I have already remarked the parasitism of the species last de- 
seribed, and Siphonophora minor was not less subject to this kind 
of attack. Indeed, even the specimens kept in the breeding cages 
throughout the summer, were many of them killed by parasites be- 
fore autumn. 
These insect enemies are frequently rather slow in concentrating 
for attack, the lady-bugs and the Syrphus flies not usually com- 
mencing to reproduce until the spring is well over, and the para- 
sitic. Hymenoptera not commonly becoming numerous enough to 
make any decided impression upon the host species until the latter 
have themselves appeared for some time in destructive numbers. It 
*It is worthy of remark that many even of these partially subterranean individuals 
had been recently parasitized, showing that their hymenopterous enemies follow them 
below the surface. 
+I decline to call the thread-like terminal part of the last joint of the antennz, com- 
mon to many plant-lice, a separate article. The fact that it is really continuous with the 
thicker basal portion is of easy observation, the two parts being separated only by a 
large sensory pore, beyond which the joint suddenly narrows. I see no sufficient reason 
for misrepresenting the facts by considering this an articulation, especially as in some 
forms (like Schizoneura panicola) the terminal filament is reduced to a short thick lobe, 
which is not then called an article. 
