CHARACTERS OF THE GENERA OF APHIS AND COCCUS. 93 
Ex. T. Physapus, Linne . Wood, vol. i. p. 118,, pi. XLII. 
It is not improbable but that each genus of flowering plants (if 
not each species) may have a species of Tlirips peculiar to it; 
British writers, however, have noticed but nine species of this genus: 
they are all, doubtless, injurious to plants in bloom. The above 
example is said to inhabit rye, and to destroy the spikes. 
VI. Fam. Aphids, Leach. 
Antenna with six, seven, or eight joints; females generally 
wingless. 
1 . Gen. Aphis, Linne (Plant-louse). 
Snout (rostrum) bent under the breast; antenna longer 
than the thorax; ivings four, or wanting; feet formed 
for walking; abdomen mostly furnished with two horn¬ 
like processes. 
Ex. A. Ros^e, Linne. Wood, v. i. p. 112, pi. XXXIX. 
These pests are exceedingly prolific. Reaumur proved by experi¬ 
ment, that one Aphis may be the progenitor of 5,904,900,000 descend¬ 
ants, during its life; and further supposes that in one year there may 
be twenty generations. For its history, and many very curious and 
interesting details, see the sixth volume of the Linnean Society's 
Transactions; Bingley’s Animal Biography (12mo ed.), vol. iv. p. 73, 
and Extracts from Reaumur and others, respecting this, and allied 
species and genera in Rennie’s Insect Architecture, Transformations, 
and Miscellanies. 
But forty-eight British species have been noticed. It is not impro¬ 
bable but that nearly every species of plant may have its peculiar 
species of Aphis. 
2. Gen. Eriosoma, Leach. 
Sjiout (rostrum) bent under the breast; antenna short and 
thread-shaped (filiform) ; body covered with a soft down or 
wool. 
Ex. E. Mari, Leach ; Laniger, Illiger. 2 Hort. Trans. 
162. pi. XI. Rennie’s Insect Miscellanies, p. 179. figs. 
a. b. c. ' 
<c The Eriosomata form what are called improperly galls, on the 
stalks of trees near their joints, and knobs, which are in fact excres¬ 
cences caused by the efforts of nature to repair the damage done to the 
old trees, by the perforation of those insects, whose bodies are covered 
with down.”— Leach. 
Twelve species only have been enumerated; no doubt they are much 
more numerous. 
3. Gen. Alekoydes, Latr. 
Snout (rostrum) bent under the breast ; antenna six-jointed. 
