Scientific American Supplement, No. 388, June 9, 1883 eBook

This eBook from the Gutenberg Project consists of approximately 147 pages of information about Scientific American Supplement, No. 388, June 9, 1883.

[Illustration:  FIG 5.—­Corthylus punctatissimus.]

Should this species become abundant and widely dispersed, it could but exercise a disastrous influence upon the maple forests of the future—­G.  Hart Merriam, M D, in American Naturalist.

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(Tetranyehus telarius.)

The red spider is not correctly speaking an insect, though it is commonly spoken of as such, neither is it a spider, as its name would imply, but an acarus or mite.  Whether its name is correct or not, it is a most destructive and troublesome pest wherever it makes its presence felt, it by no means confines itself to one or only a few kinds of plants, as many insects do, but it is very indiscriminate in its choice of food, and it attacks both plants grown under glass and those in the open air.  When these pests are present in large numbers, the leaves on which they feed soon present a sickly yellow or scorched appearance, for the supply of sap is drawn off by myriads of these little mites, which congregate on the under sides of the leaves, where they live in a very delicate web, which they spin, and multiply very rapidly; this web and the excrement of the red spider soon choke up the pores of the leaves, which, deprived of their proper amount of sap, and unable to procure the carbon from the atmosphere which they so much need, are soon in a sorry plight.  However promiscuous these mites may be in their choice of food plants—­melons, cucumbers, kidney beans, hops, vines, apple, pear, plum, peach trees, limes, roses, laurustinus, cactuses, clover, ferns, orchids, and various stove and greenhouse plants being their particular favorites—­they are by no means insensible to the difference between dryness and moisture.  To the latter they have a most decided objection, and it is only in warm and dry situations that they give much trouble, and it is nearly always in dry seasons that plants, etc., out of doors suffer most from these pests.  Fruit trees grown against walls are particularly liable to be attacked, since from their position the air round them is generally warm and dry, and the cracks and boles in the walls are favorite places for the red spider to shelter in, so that extra care should be taken to prevent them from being infested, this may best be effected by syringing the trees well night and morning with plain water, directing the water particularly to the under sides of the leaves, so as, if possible, to wash off the spiders and their webs.  If the trees be already attacked, adding soft soap and sulphur to the water will destroy them.

[Illustration:  FIG. 1—­Red Spider (magnified).  A 1.  Ditto (natural size). 2.  Underside of head. 3.  Foot. 4.  Spinneret.]

Sulphur is one of the most efficient agents known for killing them, but it will not, however, mix properly with water in its ordinary form, but should be teated according to the following recipe: 

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Scientific American Supplement, No. 388, June 9, 1883 from Project Gutenberg. Public domain.
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