CHALCIDIDjE. CHRYSIDID^. 165 



691. The family CHALCIDID.E, or Chalcis tribe, is composed of 

 a great number of parasitic insects, distinguished by their 

 generally very minute size, (their length seldom exceeding a 

 line or two,) their brilliant metallic or variegated colours, and 

 their nearly veinless wings. Like the Ichneumonidae, they are 

 all parasitic upon other insects in their early states ; the majority 

 infesting the larvae and pupas ; but some, from their minute 

 size, being reared within the eggs of other insects. They are 

 especially destructive to Lepidoptera ; but they will also attack 

 the species of most of the other Orders. Not unfrequently they 

 deposit their eggs in various kinds of galls, formed by the agency 

 of the preceding families; and their progeny, when hatched, 

 attack and subsist on the larvae inclosed within : and there are 

 some species, whose larvae are parasitic upon those of other para- 

 sitic insects. Lastly, the CHRYSIDIDJS, or Ruby-tailed Flies, 

 constitute a small group, distinguished by having the abdomen 

 attached to the thorax by a short peduncle or foot-stalk, and 

 composed of only from three to five segments, the remainder 

 being formed into a tubular apparatus, capable of being drawn 

 together or extended like a telescope, and having a minute sting 

 or ovipositor at its extremity. These insects, although but of 

 small or moderate size, are amongst the most splendid of our 

 native species ; being adorned with brilliant metallic tints, 

 usually blue and green on the head and thorax, and a fiery 

 copper-colour or ruby on the abdomen ; hence they have been 

 termed the humming-birds amongst insects. They may be 

 observed during the hottest sunshine, flying and running with 

 great vivacity over walls, palings, sand-banks, and occasionally 

 upon flowers (especially those of the Umbelliferae) and leaves. 

 Their economy has not been fully made out ; but there is reason 

 to believe that the females do not insert their eggs in the 

 bodies of other insects, but take an opportunity of depositing 

 them in the nests of the different Wild-Bees and other Hymen- 

 optera, during the period when the latter are provisioning their 

 nests for the support of their own progeny; which is thus 

 starved by the intruder, whose voracity is such as to require 

 the whole supply of food that had been prepared for the legiti- 



