ORDER HYMENOPTERA: ANTS, BEES, WASPS, ETC. 223 



damage crops, and the Horn-tails {SiricidcB), whose larvs 

 bore into the trunks of trees and spoil timber. In the Saw- 

 flies the ovipositor consists of a pair of broad plates, serrated 

 on the ventral edge, which are retractile into a pair of 

 sheaths ; in the Horn-tails the ovipositor is a long slender 

 tube embraced by a pair of long slender sheaths. 



2. Petiolata. There is a " waist " formed by the true 

 2nd (apparent ist) abdominal segment, or sometimes by the 

 true 2nd and 3rd abdominal segments ; it may be of great 

 length, or it may merely be a constriction, and it gives the 

 abdomen very free play. The larva has no legs. This 

 enormous suborder is arranged in three divisions, namely : 

 (i) the parasitic Hymenoptera, or Parasitica; (ii) a small 

 intermediate group in which the ovipositor is peculiar and 

 retractile and has something the look of a sting — the Tubuli- 

 fera ; and (iii) the true stinging Hymenoptera, or Aculeata. 



i. Parasitica. The female has an ovipositor, not a sting ; 

 the trochanter of the legs is usually composed of two pieces. 

 This group includes a prodigious number of Hymenoptera, 

 many of which are minute, though some are of good size. 

 The larvae of some of them are vegetable-parasites, and form 

 galls on plants ; but the larvae of the great majority are 

 parasitic generally in (sometimes on) the larvae or pupae, 

 sometimes in the eggs, of other insects. The victimised 

 larva is not immediately killed, but lives for some time, and 

 may even, in due season, pupate ; but if this happens, the 

 parasitic Hymenopteron continues to live at the expense of 

 the victim-pupa and ultimately pupates in the latter, so that 

 for the latter all is vanity. The parasitic Hymenoptera 

 thus destroy a vast number of insects — chiefly caterpillars, 

 but also aphides, the larvae of beetles. Dipterous maggots, 

 etc. ; it is a common experience in the tropics to find that an 

 insect larva which is being bred with a view to specific 

 identification yields from its pupa nothing but parasitic 

 Hymenoptera. The following families may be noticed : — 



(a) CynipidcB ; Gall-flies. These are small, or minute, 

 Hymenoptera, usually of a shiny black colour : they may 

 be recognised by the relatively enormous size of the terga 

 of one or two of the anterior segments of the abdomen and the 

 telescoped appearance of the posterior segments, and by the 



