224 ENTOMOLOGY FOR MEDICAL OFFICERS 



absence of a stigma, or opaque spot near the middle of the 

 anterior margin of the front wing : the larvae live in galls 

 (of which the oak-apple and the mossy rose-gall are good 

 examples), which are closed^ so that the insect when trans- 

 formed has to eat its way out. 



(b) Ichneumonidce ; Ichneumon-flies. Though some of 

 these are minute, many are of large size. The body 

 is long and slender and, in the female, ends in an 

 ovipositor which is sometimes of enormous length; the 

 antennae are long and slender. The eggs are commonly 

 laid in caterpillars, which are ultimately killed by the larvae. 



(c) CkalddidcB (Fig. 98). These are usually small, often 

 very minute, and generally have a bronzy sheen (xaX/co? = 

 copper or brass). The wings have no cells and usually only 



Fia. 98.— A Chaloid Fly, greatly enlarged. 



a single vein, which branches, and they are generally covered 

 with fine hairs. Most of the species of this large family are 

 parasitic on the larvae, pupae, or eggs of other insects, and it 

 has been observed of late that the maggots of several species 

 of MuscidcB are subject to the mortal attack of Chalcis-flies, a 

 fact which is of importance to the medical officer. 



(d) Proctotrypidce, or Oxyura. These also are minute 

 insects resembling the Chalcis-flies in form and habits, but 

 differing from them in the absence of metallic lustre and, 

 as regards the female, in having the abdomen pointed, with 

 the ovipositor issuing from its tip. 



ii. Tubulifera. This division includes the single family 

 ChrysididcB, or Cuckoo-wasps. These are easily recognised 

 by their brilliant (often green) metallic lustre ; by their thick, 

 extremely hard, coarsely pitted exoskeleton ; by their ability 

 to roll themselves up, owing to the ventral surface of the 

 abdomen being concave; and by the long, transversely 



