Pee.] the HOT-HOUSE. 173 
2. The Acarus, commonly called the Red Spider. This is of 
the order Aptera. Characters. Eyes placed on the sides of the 
head, remote from one another. Mouth or proboscis, formed by a 
small pointed rostrum inclosed in a sheath. Antennas, shorter than 
the proboscis. Feet eight. They are oviparous. 
This is a pest to almost every kind of plantsj for this insect is 
not only pernicious to most plants kept under glass, but also to 
many growing in the open air. 
In hot dry weather the increase of these insects is exceedingly 
rapid, and when they become numerous, they, by various means, 
commit great havoc on plants; for this insect with its proboscis, 
perpetually wounds the fine or capillary vessels of plants, and ex- 
tracts their nutricious juices. It also works a web about the leaves 
and over the tender buds and tops of the plants, in such a manner as 
nearly to suffocate them, and prevent their vegetation. 
This insect does not seem to be affected by fumigation made with 
any ingredients hitherto discovered; and it is probable that the ap- 
terous insects, or those without wings, are not so much aifected by 
fumigation as the winged tribe. 
However, the mixtures recommended for destroying the insects 
on the pine-apple, will have the same effect on this. Plants greatly 
infested, and growing in pots, when their tops are not very large, 
may with great facility be dipped in a convenient vessel filled with 
those mixtures: the top of the plant need only remain a short time 
therein, and it should then be placed in a shady place to prevent 
its drying too rapidly. 
These insects very frequently reside on the under side of the 
leaves, and, when very numerous, they work so thick a web there- 
on, that it sometimes prevents the mixture from entering into cer- 
tain hollow parts of the leaves, by which means a few escape un- 
hurt; in which case it will be proper for the plants to undergo the 
same operation the succeeding afternoon, which will most assuredly 
destroy all that escaped before. 
Large or climbing plants, when their leaves are large, as for in- 
stance the vine, must be dressed with the mixture by means of a 
sponge-, this has the appearance of a tedious operation; but in a 
dark day when the house is not very warm, a person will make 
considerable progress therein in the course of a few hours. 
The keeping of the house in a moist state, by watering the walks 
and flues late in the evening, and the frequent sprinkling of the 
plants with water, contributes to retard the progress of these insects, 
which are very impatient of much moisture. This reduces them to 
a temporary state of inaction, but will not destroy them. 
3. The Thrips. Order Hemiptera. Characters. Rostrum, 
small and obscure. Antennae, as long as the thorax. Body slender, 
of an equal thickness in its whole length. Abdomen reflexible, 
being generally bent upwards. Wings four, incumbent on the back 
of the insect, narrow in proportion to their length, and cross one 
another at some distance from their base. Feet six, the tarsus of 
each foot having only two articulations. 
This is also a very pernicious species of insect, and is very com- 
