6l6 THE STUDY OF INSECTS. 



that not all of the members of this family are developed 

 in galls, and that galls are produced by many insects 

 that do not belong to this family. Galls made by mites, 

 plant-lice, flies, and moths have been described in the pre- 

 ceding pages, and galls are also produced by beetles and cer- 

 tain other insects ; but the great majority of these strange 

 growths are made either by mites, plant-lice, or true gall- 

 ' flies (Cynipidae). 



The galls made by mites and plant-lice have open mouths, 

 from which the young of the original dweller escape. But 

 in the case of the gall-flies the gall is closed, and a hole must 

 be made by the insect in order to emerge. Moreover, there 

 is no reproduction of insects within the galls of gall-flies, as 

 there is within the galls of mites and plant-lice. Many 

 species of gall-flies undergo their transformations within 

 their galls; while in other species the full-grown larva leaves 

 the gall and enters the earth to transform. But in each case 

 the adult female provides for the production of new galls, 

 in which their young are to develop. 



In the adult gall-fly the abdomen is usually much com- 

 pressed. It is joined to the thorax by a short peduncle, the 



first abdominal segment (Fig. 

 745). The second and third 

 abdominal segments are large, 

 and the remaining segments, 

 usually five in number, are 

 short, and each is more or less 

 covered by the preceding seg- 

 ment. Concealed within these 

 segments is the long, partially 

 coiled, very slender ovipositor, 



the abdomen. The wings of gall-flies have compara- 

 tively few veins, and the fore wings lack the stigma ; some 

 forms are wingless. The antennae are not elbowed, and 

 consist of from thirteen to sixteen segments. The larvae 



