Wasps, Bees, and Ants 



465 



leaving the skeleton of tough, fibrous veins; often only the upper surface 



of the leaf is fed on. Some of them cover the body with a white, waxy secre- 



tion, and some, when disturbed, emit a 



malodorous fluid from the mouth or from 



pores in the skin. When full-grown, they 



crawl down to the ground, burrow into it, and 



pupate within a little cell sometimes lined 



with a thin silken cocoon. Some of the larvae 



.. . n . . . , , , FIG. 652. The currant-slug, larva 



live in gall which develop about them; one of the cur rant saw-fly, Nematus 



uentricosus. (Two and one-half 

 times natural size.) 



such species is common on willows. The 



adults mostly have rather broad somewhat 



flattened bodies and head, are quietly colored, blackish, reddish, brownish, 



and usually quietly mannered, but fluttering about in the trees at egg-lay- 



ing time. 



It has been noted that numerous species of saw-flies can produce young 



FIG. 653. The currant-stem girdler, Janus integer, a saw-fly at work girdling a stem 

 after having deposited an egg in the stem half an inch lower down. (Photograph 

 by Slingerland; natural size.) 



from unfertilized eggs (parthenogenetic reproduction), and in some species 



