196 PROTECTION AGAINST INSECTS. 



and only partially covering the abdomen, sometimes imperfectly 

 developed. 



Larva with horny head and 22 legs. 



The eggs are laid in moist soil, and the larvae pupate in oval, 

 hollo wed-out lumps of earth. 



The larvae and images devour insects. 



The common Panorpa communis, L., flies about around low 

 bushes and hedge-rows, and destroys the pupae of Liparis 

 salicis, L., etc. 



2. Sialidac. 



Imagos of moderate size, with broad head, long neck and 

 fairly broad abdomen ; with 3 ocelli, sometimes absent. 

 Mouth-parts free, fully developed. Antennae short, usually 

 setiform, and many- jointed. Wings many-celled, colourless, 

 with bristles on the veins, sloping like a roof when at rest. 



Larva with 6 short and stout legs. Pupa elongate, with the 

 limbs free. 



Example. Ehaphidia, L. The perfect insects fly in May 

 and June, and lay their eggs in or under the bark of Scots 

 pine or spruce. The snake-like brown larvae live through the 

 winter, and pupate in the spring, without any cocoon ; about 

 2 to 8 weeks later the imagos emerge. E. notata, Schum., is 

 very useful ; its larvae greedily destroy the eggs and larvae of 

 other insects which they find on and under the bark ; common 

 in coniferous woods. 



3. Hemerobiidae (Lace -winged flies). 



Imagos long and delicate. Head small, with large hemi- 

 spherical eyes ; no ocelli. Mouth-parts free. Antennae long, 

 setiform, many- jointed. 



Wings similar in size, transparent and multicellular, sloping 

 like a roof when at rest. Legs slender. 



Larva elongate, and narrowed towards the ends, with two 

 slender curved mandibles perforated for sucking, and 6 legs. 



The flight-period is in the early summer, and again in 

 autumn. The stalked white or greenish eggs are laid in 

 groups on leaves. 



