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.
plants.  The red spider lays its eggs among the threads of the web which it weaves over the under sides of the leaves; the eggs are round and white; the young spiders are hatched in about a week, and they very much resemble their parents in general appearance, but they have only three pairs of legs instead of four at first, and they do not acquire the fourth pair until they have changed their skins several times; they are, of course, much smaller in size, but are, however, in proportion just as destructive as the older ones.  They obtain the juices of the leaves by eating through the skin with their mandibles, and then thrusting in their probosces or suckers (Fig. 2), through which they draw out the juices.  These little creatures are so transparent, that it is very difficult to make out all the details of their mouths accurately.  The females are very fertile, and breed with great rapidity under favorable circumstances all the year round.

The red spiders, as I have already stated, are not real spiders, but belong to the family Acarina or mites, a family included in the same class (the arachnida) as the true spiders, from which they may be easily distinguished by the want of any apparent division between the head and thorax and body; in the true spiders the head and thorax are united together and form one piece, to which the body is joined by a slender waist.  The arachnidae are followed by the myriapoda (centipedes, etc.), and these by the insectiae or true insects.  The red spiders belong to the kind of mites called spinning mites, to distinguish them from those which do not form a web of any kind.  It is not quite certain at present whether there is only one or more species of red spider; but this is immaterial to the horticulturist, as their habits and the means for their destruction are the same.  The red spider (Tetranychus telarius—­Fig. 1) is very minute, not measuring more than the sixtieth of an inch in length when full grown; their color is very variable, some individuals being nearly white, others greenish, or various shades of orange, and red.  This variation in color probably depends somewhat on their age or food—­the red ones are generally supposed to be the most mature.  The head is furnished with a pair of pointed mandibles, between which is a pointed beak or sucker (Fig. 2).  The legs are eight in number; the two front pairs project forward and the other two backward; they are covered with long stiff hairs; the extremities of the feet are provided with long bent hairs, which are each terminated by a knob.  The legs and feet appear to be only used in drawing out the threads and weaving the web.  The thread is secreted by a nipple or spinneret (Fig. 4) situated near the apex of the body on the under side.  The upper surface of the body is sparingly covered with long stiff hairs.—­G.S.S., in The Garden.

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