CHAP, xiv.] Insect Enemies 319 



to be found in the larval galleries of the Pine-beetle (Hylurgus 

 piniperda} under the bark of Scots Pine and the lady-birds 

 (Coccincttidae\ of which Cocdnella septempunctata and C. bi- 

 punctata are of most frequent occurrence, whilst several species 

 of the genus Halyzia are only to be found in the woods, 

 particularly in Spruce and Pine woods. 



Among the Hymenoptera, the digging wasps (Sphegidae) stun 

 caterpillars, beetles, plant-lice, &c., with their stings, drag them 

 to their holes, and then utilize them for breeding places (so 

 that they are both predatory and parasitic); the wasps 

 ( Vespidae)) and in particular the hornet ( Vespa crabro] itself 

 injurious to Ash prey on moths and flies; whilst the ants 

 (Formicidae], which live in colonies of thousands in their 

 breeding-mounds, consume enormous numbers of larvae of 

 various descriptions. 



Among the Diptera, the predatory flies (Astlidae\ which 

 breed principally in sandy localities, attack and feed on many 

 other kinds of insects ; whilst the humming or chirping flies 

 (Syrphtdae) are more frequently to be found in orchards than 

 in the woods. 



Although the Neuroptera contribute the scorpion-fly (Pan- 

 orpa\ the camel-necked flies (Rhaphidia\ the gold-eyed fly 

 (Hemerobia perld), and the ant-lion (Myrmeleon\ which are all 

 useful in preying on noxious insects (the last-named un- 

 fortunately also diminishes the number of useful ants), whilst 

 the Hemiptera furnish the scaly and other bugs (Pentatomidae 

 and Reduviidae\ and the Orthoptera produce the dragon- 

 flies (Libtllulidae\ yet the predatory species among these 

 three orders are comparatively inactive as compared with 

 those in the first-named three. 



2. The Parasitic Species, the chief insect enemies of the 

 noxious varieties, are to be found among the ichneumon-flies 

 (Ichneumonidae) of the Hymenoptera, and the parasitic-flies 

 (Tachininae\ a group of the Muscidae family of the Diptera. 

 In fact, it is mainly to fungoid diseases and to the Ich- 



