HYMEXOPTERA. 431 



The most that we can do towards checking their ravages, will 

 be to destroy the females, whenever they are found laying 

 their eggs. 



The four-winged gall-flies have very little outward resem- 

 blance to the saw-flies and horn-tailed wood-wasps. They 

 agree with them, however, in boring into plants, and in laying 

 their eggs therein. Vegetation does not often suffer much 

 injury from their attacks, and it is only on account of the very 

 singular productions, called galls, arising from the irritating 

 punctures of these insects, that the attention of cultivators is 

 at all likely to be drawn to them. There are some two-winged 

 flies, and also some other insects, which produce various kinds 

 of excrescences or galls on plants ; but these, now under con- 

 sideration, are very small, four-winged insects, belonging to 

 the order Hymenoptera, and distinguished by the following 

 peculiarities. The head is small; the antennoB are rather 

 short, slender, and thread-like; and the thorax is thick and 

 hunched. The abdomen or hind body, viewed sidewise, ap- 

 pears round or oval, but it is sharp-edged above and below, 

 very thin or pinched up at the sides, and is hung to the thorax 

 by a very short and slender stem. The fore wings are rather 

 long, and have only a few veins in them; the hind wings are 

 small, and seemingly veinless. The borer of the females is 

 very long, and slender, concealed in the under side of the hind 

 body, the curvature whereof it follows, and is capable of being 

 straightened and thrust out of a naiTow chink, which is cov- 

 ered by two little, grooved, sheath-like pieces, that serve to 

 conduct the eggs into the holes made with the instrument. 

 The genus containing most of the gall-flies was called, by 

 Geoft'roy, Diplolepis, that is, double scales, on account of the 

 two pieces that cover the opening for the borer in the hinder 

 part of the abdomen. The same insects, however, had pre- 

 viously been placed by Linnaeus in the genus Ct/nips, so called 

 from a word used by ancient authors to designate some small 

 piercing insect. The Linnaean name, though for some time 

 rejected, has been restored to the gall-flies, which accordingly 

 are now included in a family called Cynipid.e. The punctures, 

 made by these insects in the leaves, buds, stems, and roots of 



