TYPICAL GROUP GALL WASPS 



2981 



with black spots on the back, sometimes blending to form a central band. The 

 pretty brush-horned rose sawfly {Hylotoma ros&), which in size and color closely 

 resembles the turnip sawfly, extends throughout Europe, where it is common 

 wherever rose trees occur; the larva being found from July to October on both 

 the wild and cultivated roses. When turning to a pupa, it spins an outer 

 meshed envelope, and a more densely woven inner one; early larvae pupating at 

 once, and emerging as perfect insects early in August. The later broods, however, 

 pass the winter in the pupa case, and appear in the following spring. The female 

 makes an incision on the twigs of rose bushes, in which she lays her eggs, after 

 which the twig withers away. 



TYPICAL GROUP SUBORDER Petiolata 



The insects belonging to this second subdivision of the order are distinguishable 

 from the last by the petiole, or short stalk joining the abdomen to the thorax. Some- 

 times this stalk is so short that the abdomen and thorax are closely united, while in 

 others it is longer, and thus these characteristics form a fairly natural subdivision of 

 the Petiolata into the pseudosessile and pedicellate forms. For general purposes they 

 may, however, be divided into Parasitica, or those in which the females are fur- 

 nished with an ovipositor, and Aculeata, or those in which the ovipositor has be- 

 come modified into a retractile sting. 



GALL WASPS Family CTNIPID^E 



Of the former, or parasitic section of the suborder, our first representatives are 

 the gall wasps (Cynipidce} , all of which are small and inconspicuous insects, vary- 

 ing in color from black to brown and brownish red. The wings are furnished with 



GREEN SAWFLY, Tenthredo scalaris. 

 (Natural size.) 



few nervures, and the dark stigma on the anterior margin is absent; while in some 

 species the females have the wings either rudimentary or altogether wanting. Of 

 the galls so common on the foliage of trees and other plants, some are produced by 



