544 HYMENOPTEEA. 



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 consideration are very small, 

 four-winged insects, belonging to the order Symenoptera, 

 and distinguished by the following peculiarities. The head 

 is small ; the antennse are rather short, slender, and thread- 

 like ; and the thorax is thick and hunched. The abdomen 

 or hind body, viewed sidewise, appears 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 narrow chink, which 

 is covered 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 Geoffroy, 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, how- 

 ever, had previously been placed by Linnseus in the genus 

 Gynips, so called from a word used by ancient authors to 

 designate some small piercing insect. The Linnsean name, 

 though for some time rejected, has been restored to the gall- 

 flies, which accordingly are now included in a family called 

 Cynipid^. The punctures, made by these insects in the 

 leaves, brfds, stems, and roots of plants, are followed by 

 swellings of the wounded parts, which increase rapidly in 

 size, and become spongy or pulpy within. The thin-skinned 

 eggs, dropped into the punctures, grow awhile, by absorb- 

 ing the sap around them, and, when at length they are 



