Page:VCH Surrey 1.djvu/212

 A HISTORY OF SURREY pupx may be collected in an hour's time by sweeping the grass and low herbage. The Ulopidce and Paropidce are only poorly represented in this county. JASSID^E Grass-jiies This sub-family, which is numerous in species and genera, includes the insects commonly known as grass-flies. They affect all kinds of trees, shrubs, herbs and gramineae. Though small, many are beautiful objects under a microscope when viewed by reflected light. The pretty little leaping Tettigonia viridit is very common in the Haslemere district, and may be found coursing up and down the stems of coarse meadow- grasses in midsummer. The "Jassidce are included in the Membraddce by Carolus Stal, but it is not obvious why he thus located them. APHIDID^E Aphides Green-Jiies Comparatively few realize the fact that the larger part of the animal matter in the world is the result of insect agency. Except through the medium of foes and parasites the balance between vegetable and animal life would not be maintained. Blight and insect-pest would render useless all the efforts of the agriculturist. The wonderful multiplication of aphides, made possible by the process of parthenogenesis and their spread through the dimorphism of both sexes, is familiar to us. Thus under suitable conditions clouds of these insects may appear within a few days in localities where they were before only known as units. Crops. The agriculturist has perhaps no greater aphis-foes to contend with than Siphonophora granaria, S. pisi, Rbopalosiphum rapce and Aphis rumicis. The first-named species deposits its ova on the flower- stalks of wheat and other corn-crops, and often destroys the produce of many acres in a few days. There may be as many aphides on one corn- head as there are grains of seed, which last become shrivelled and diseased from their attacks. Fortunately more than half of these aphides will be found stung or pierced by one of several kinds of ichneumon flies, but this check mostly comes too late to save the character of the crop. Siphonophora fist, known to farmers as the green dolphin, attacks legu- minous plants and particularly the field pea. It is more common in some seasons than others, and the companies are mixed with other allied species. Aphis -uiciee often crowds the stalks of the wild vetch. Rbopalosipbum rupee is almost omnivorous, and attacks indiscriminately the mangold, the swede and turnip, the kohl-rabi and the potato. As injuring the last plant it was named by Smee Aphis vasfator, and was thought by him to cause the potato-rot. A. rumicis does great injury to the broad-bean, and has the common name of the black dolphin. It may be known, as 170