USEFUL DIPTERA. 195 



Common species. Syrplms pirastri, L., frequently found on 

 fruit trees and on Scots pine. S. lalteatus, De Geer. 



3. Muscidae (Flies). 



linages generally short and stout. Eyes, as a rule, densely 

 covered with hairs; ocelli present. Proboscis fleshy. Antennae 

 short,. 3- join ted, the terminal joint the largest, not ringed, fur- 

 nished with a bristle on its dorsal surface. Wings of moderate 

 size, with few longitudinal veins. Legs strong and moderately 

 long. Abdomens, with 4 7 apparent segments, generally 

 scantily hairy, sometimes with an ovipositor in the ? . 



Larva without legs or distinct head, soft, and generally 

 whitish. 

 . Pupa coarctate, round or elliptic, brown or blackish. 



Flies lay their eggs sometimes in decomposing substances, 

 sometimes on living animals. 



In forest economy, only the parasitic flies are of importance, 

 of which the chief are the Tachininae. 



Many species of these flies are parasitic in or on the larvae 

 and pupae of other insects, as moths and sawflies. Their im- 

 portance is somewhat less than that of the ichneumon-wasps, 

 but they, nevertheless, destroy great numbers of insects. They 

 pupate generally outside the host, on or under the ground. 

 The larvae not only suck the juices of their hosts, but, unlike 

 those of the ichneumon-wasps, devour their viscera. 



Species. Echinomyia fera, L., frequent on larvae of Liparis 

 monacha and Panolis piniperda. 



The sub-family Anthomyinae contains a few species which are 

 injurious to forest trees, f or example, A nthomyiaruJiceps,Weig. 

 According to Theodor Hartig the larva of this species which 

 lives in the ground, especially in burned sods, eats the seeds 

 and roots of coniferous seedlings. 



ORDER IV. NEUROPTERA. 

 1. Panorpidae (Scorpion-flies). 



Imac/os of moderate size, head prolonged into a beak bearing 

 the mouth at its extremity. Antennae many-jointed, setiform. 

 Both pairs of wings of equal size, with few intersecting veins, 



