Chalcis

Chalcis, a typical genus of a large family of Hymenopterous insects, not unlike small wasps. The family (Chalcididæ or Pteromalini) has this great importance that the larvæ of its members are parasitic in the eggs, larvæ, or pupæ of other insects, and as some of the latter are very destructive to plants, their parasites are animals to be thankful for. Thus forms so different as the cabbage butterfly and the destructive Hessian fly have their attendant Pteromalini. Many of the so-called gall-wasps (Cynipidæ) which cause many of the commonest galls—for instance on the oak, or the curious bunches on rose and briar bushes—are preyed upon by Chalcididæ. Some of the hosts of these Chalcidæ are themselves parasitic, and thus we have parasites within parasites, or double parasitism, there being in this case no honour among thieves. Altogether over 2000 species of Chalcididæ are known.