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 j 

 pupate within a little cell sometimes lined 



with a thin silken cocoon. Some of the larvae 



.. . i . i j , i FlG. 652. The currant-slug, larva 



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



such species is common on willows. The ventricosus. (Two and one-half 

 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 



FlG. 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 



