G84 JOURNAL, BOMBAY NATURAL HISTORY SOCIETY, Vol XVI. 



balanced by the fact that the same families contain Insects which are- 

 parasitic upon, and therefore lessen the numbers of, our useful Insect 

 friends. In spite of this, however, in the case of serious increases in the 

 numbers of an Insect pest such as a plague of caterpillars, or abnormal 

 increases in plant lice (Aphidce) and scale Insects (Coccidce), &c, man 

 is often deeply indebted to his hymenopterous allies. In this respect the 

 ChalcididoB undoubtedly stand out prominently ; it has already been as- 

 certained that the family contains species of undeniable importance and 

 the further study of the group in India will well repay the trouble ex- 

 pended upon it. We have seen (in Chapter V) that members of the 

 family attack such different pests as the sugarcane borer (Child simplex), 

 the tea scale bug (Chionaspis thece), the so-called cheroot weevil (Lasio- 

 derma testaceum) and tea and sal leaf defoliating caterpillars. Other species 

 have been found parasitic upon blue pine (Polygraphias, Pityogenes,) and 

 deodar (Scolytus) pests. It has also been discovered, however, that it 

 contains members which are parasitic upon beneficial Insects as, e.g., Peri- 

 lampus considered to be parasitic upon some dipterous friends. Nest to the 

 Chalcididce we may mention the Ichneumonidce, which are par excellence 

 a parasitic group, more especially affecting the caterpillars of Lepidoptera. 

 This family likewise is not entirely a beneficial one since it commits a 

 considerable amount of injury amongst silkworms reared by man for 

 their products, and this injury at times involves heavy pecuniary 

 loss. Defoliating pests of all kinds are kept in check however, such 

 as the Lymantrias of the tea and sal tree by Chalcis eup>loea r 

 Acronycta ancedina of the horse chestnut by Ophion aureolatus ; Hyblcea 

 puera the common teak defoliator by species of Glypta, Pimpla, &c. ; 

 defoliating Satumiidae by Pimpla punctata? ; the wheat and rice 

 weevil by Pteromalus oryzce, &c. Although essentially a Lepi- 

 dopterous larva-parasiting group, the Ichneumonidce do not, however, 

 confine themselves to caterpillars. The genera of magnificent Insects 

 known as Thalessa and Rhyssa attack wood-feeding grubs and are in 

 consequence of considerable importance in the forest and orchard on this 

 account. We have seen that a species of Rhyssa is parasitic upon the 

 fine sirex wood-borer of Spruce (Sirex imperialis). Little is at present 

 known about the parasitic family Proctotrypidoi which contains how- 

 ever the important Insect Platygaster oryzce which is parasitic on the 

 rice fly pest ( Cecidomyia oryzce) or of the Braconidce which greatly 

 resemble the true Ichneumonidce. Both these families will certainly 



