[hahrixgton] CANADIAN PROCTOTBYPID^ 173 



Proctotrypids are also much less active in their movements, and, when 

 taken with a sweeping-net, usually walk lazily about and are slow to take 

 flight; often, also, they remain motionless, "shamming dead," with the 

 antennœ folded beneath the body. Chalcids, on the contrary, are quick 

 in taking wing, as a rule, and thus a smaller proportion of the specimens 

 taken in a net will be secured. 



Sweeping among the luxviriant herbage of damp localities is the 

 most expeditious method of making a collection, but some species occur 

 only in drier situations. A more valuable mode of obtaining specimens 

 is to breed them, thus obtaining, what is infinitely more valuable than 

 the specimens themselves, records and observations of their life-histories. 

 In the great complex of insect life these minute creatures hold a very 

 important place, as they are all true parasites, attaining their develop- 

 ment at the exj3ense of other insects or of arachnids, and thus forming a 

 great check uj^on the undue multiplication of many forms. All the 

 members of one of the largest subfamilies are exclusively egg-parasites, 

 infesting especially the eggs of lepidoptera, hemiptera, orthoptera and 

 spiders. Usually one specimen only develops in an egg, but some 

 species are so small that several may find sufficient nourishment therein. 

 The remaining forms live in the bodies of insects in their larval and 

 pupal stages. The entomologist who rears insects in any order has thus 

 opportunities of breeding these parasites and of recording his observa- 

 tioiis as to their hosts. 



The following are the habits attributed to the several subfamilies- 

 The Bethylinœ are believed to be largely parasitic on coleopterous larvœ, 

 as they have been reared from galls and fungi inhabited by such larvae ; 

 other genera inhabit ant-nests, and some prey upon microlepidopterous 

 larvœ. The Dryininœ confine their attacks to certain groups of homop- 

 terous insects, and the peculiar pincer-like claws of the females of most 

 genera are supposed to enable them to grasp the larval forms of such 

 horaoptera. The Ceraphroninœ are chiefly parasitic on aphids and ceci- 

 domyids. The Scelioninre are true egg-parasites, and may be readily 

 reared from the eggs of lepidoptera, hemiptera, orthoptera and spiders. 

 The PlatygasterinsB infest the larva? of the families Cecidomyidœ and 

 Tipulidœ of the Diptera. The Helorina^, limited to the single genus 

 Helorus, are parasitic in the cocoons of Chrysopa, a neuropterous genus. 

 The Proctotrypinœ are considered to prey upon the larvae of flies and 

 beetles living in fungi, and the Belytinœ are supposed to have similar 

 habits. The Diapriinœ are thought to be confined to diptei-ous larvae, 

 but the habits of only a small proportion ai-e fully known. 



Our knowledge regarding the habits of the Canadian species is, as 

 may be easily understood, of the most meagre character, and it is most 

 desirable that information should be acquired as to the life-histories of as 

 many forms as possible. By collecting eggs and larvœ which ai)pcar to 



Sec. IV,, 1899. 11 . 



