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These industrious insects are generally loathed and destroyed, though they are extremely useful in reducing the quantity of flies, and serve as a very accurate barometer for the weather. When they are totally inactive, it is a certain sign that rain will shortly follow; but if they continue to spin during a shower, it indicates that the rain will soon be over, and that calm and fine weather will succeed.

If the weather be about to change, and become wet or windy, the spider will make the supporters of his web very short; but if the threads be extended to an unusual length, the weather will continue serene for ten or twelve days, or more, according to the length of the threads which support the web. The red spider however is very injurious and destructive to different sorts of plants and fruit-trees, especially in forcing houses. It is found particularly so to those of the forced French bean, melon; peach, vine, cherry, currant, and some other kinds. The generation and production of this insect are greatly caused and promoted by the dry warm heat that is constantly kept up in the houses which contain these sorts of plants and trees, and there are many other circumstances which combine in bringing it forth. 

It is an insect which has no wings, and the female is oviparous. Several different methods have been attempted in order to the removal and destruction of it. Constant daily watering, or washing the trees, are said to have the power of subduing it, but in the execution of the work, care is always to be taken that every part of the leaves be wetted, otherwise the insects shelter and save themselves in the dry parts, and are preserved from the effects of the water. Moisture conveyed in some way or other is certainly found to be the most destructive, of any thing yet discovered, of these pernicious insects, as well as many others that infest hot-houses. Throwing weak lime-water in a plentiful manner on the under sides of the leaves, where these insects are commonly found, will, for the most part, soon destroy them. 

The following directions have been given for the destruction of this sort of spider, when it becomes injurious to melon plants; and the same may probably be found useful for those of the forced French bean, and some other similar kinds. In cases of dry weather, and with a dry heat, melon plants are very subject to be infested with the red spider; and the appearances of it may constantly be long noticed before the insects can be seen with the naked eye, by the leaves beginning to curl and crack in their middle parts. Whenever they are discovered to be in this state or condition, and there is fine warm sunny weather, the watering of them all over the leaves, both on the under and upper sides, is advised; a watering-pot, with a rose finely perforated with holes, or a garden-engine, which disperses the water in a fine dew-like manner, being employed for the purpose. 

The work should be performed about six o'clock in the morning, and the plants be shaded with mats about eight, if the sun shine with much power, shutting the frames down closely until about eleven; and then admitting a small quantity of fresh air, letting the mats remain until about three in the afternoon, when they should be wholly taken away. The shade which is thus afforded by the mats prevents the leaves of the plants from being scorched or otherwise injured by the action of the heat of the sun while they are in a wet cooled down state. Where a southerly breeze prevails, watering them again about three in the afternoon is recommended, shutting them up close as before, to keep the heat in, which causes a strong exhalation of the moisture, and is greatly destructive of the spiders. In all these waterings, the water is to be thrown as much and as finely as possible on the under sides of the leaves, where the insects mostly lodge; the vines or stems of the plants being gently turned in that intention, taking great care not to injure them, by which means the water is capable of being easily thrown over the whole of the under sides of the leaves, it being done in a gentle manner, in the modes already suggested, so as not to wash up the mouldy matters unto the plants: the lights and sides of the frames which contain the plants, should also, at the same time, have water plentifully thrown on and against them. 

When these waterings are finished, the vines or stems of the plants are to be carefully laid down again in their former positions. And if the day be sunny, the mats may be let remain, as already directed, until the leaves of the plants become perfectly dry, air being admitted according to the heat that may be present at the time. It is likewise further advised as a precautionary measure, that, before the frames and lights, which are to contain plants of this sort, are employed, they should be well washed, both inside and out, first with clean water, and then with a mixture of soap-suds and urine; a brush or woollen rag being made use of in the operation; as by this method the ova or eggs of the spiders or other insects that may have been deposited and lodged in or on them, in the preceding season, may be cleared away and destroyed. The exhalations of the water which has been thrown upon the plants, and the frames or boxes that contain them, may also be useful in killing these insects, in other cases by keeping them in a close state. These washings should never, however, be performed in cold frosty seasons; and the water made use of in such cases should always be of the rain or soft kind.