STATE AGCICCLTURAL SOCIETY. 
115 
described : The flies, as before remarked, on their first arrival, immediately 
suck the underside of the upper small leaves of the vine, and thus they 
there deposit their young’, upon the most succulent part of the plant. The 
multiplication of the lice is so rapid, that the leaves become so thickly 
covered as scarcely to allow a pin to be thrust betweeu them. They 
quickly abstract the juices of the vine, so that the leaves assume a sickly, 
brown hue, and curl up, and the vine itself ceases to grow, and falls from 
the pole, the lice continuing till they perish for want of food ; and thus the 
crop is destroyed, and the grower may often consider himself fortunate if 
the plant recovers a due amount of vitality to produce a crop in the following 
year, for occasional!}' the hills are killed by the severity of the attack. This 
description, of course, applies only to the most severe and unusual blights.” 
The Aphides are the most evanescent of all insects. They spring up 
suddenly, in such immense numbers as to threaten the utter destruction of 
the vegetation on which they subsist, and ere long they vanish with equal 
suddenness — sometimes continuing but a few weeks, and rarely remaining 
in force longer than through one year. It thus appears, that, so long as 
the atmospherical or other influence which favors their increase, continues 
to operate upon them, they thrive and prosper, and when this influence 
passes away they rapidly decline. The writer in the Gardener’s Chronicle, 
cited above, remarks of this Aphis on the hops, “ These insects are remark¬ 
ably susceptible of atmospherical and electrical changes, and on a sudden 
alteration of the weather we have known them perish by myriads in a 
night. This was specially exemplified in the Farnham district, about the 
middle of June, 1846, which suddenly recovered from a most severe attack, 
and afterwards produced the largest crop ever known in that quarter. We 
know, also, several instances in East Kent, which occurred in the same 
year, when the planters sold their growths on the poles at a few shillings 
per acre, and these same plantations so far recovered that many of them 
afterwards produced a crop worth from 30Z. to 50 1. per acre.” 
The decline and disappearance of these plant lice is greatly expedited by 
other insects which destroy them ; and in many instances it is to these de¬ 
stroyers rather than to any atmospherical change, that the vegetation on 
which they abound becomes so suddeidy released from them. No otlnJr 
tribe of insects has so many enemies of its own class as the plant lice. The 
different species of Coccinella or lady-bugs which are everywhere so com-, 
mon, live exclusively upon the aphides, as do also the larvae of the two- 
winged Syrphus flies and the four-winged Golden-eyed flies. Superaddcd 
to these destroyers the plant lice also have their internal parasites—ex¬ 
ceedingly minute worms or maggots residing within their bodies and 
feeding upon till they kill them. Thus, whenever a tree or shrub becomes 
thronged with plant lice, these destroyers gather among and around them, 
in rapidly augmenting numbers, and subsist upon them until they have 
wholly exterminated them. Kirby and Spence (page 181) state that in the 
year 1807 the sea shore at Brighton and all the watering places on the 
south coast of England, was literally covered with lady bugs, to the great 
surprise, and even alarm, of the inhabitants, who were ignorant that their 
little visitors were emigrants from the neighboring hop-grounds, where 
each had slaiu his thousands and tens of thousands of the aphis. 
