Guide to the study of insects, and a treatise on those injurious and beneficial to crops: for the use of colleges, farm-schools, and agriculturists . re thus very serviceable to the aoricul- » C* turist, as they must annually destroy immense numbers of cat-erpillars. In Europe over 2,000 species of this family havebeen described, and it is probable that we have an equal num-ber of species in America ; G-erstaecker estimates that thereare 4,000 to 5,000 known species. The Ichneumons also prey on certain Coleoptera and Hymen-optera, and even on larvae of Phryganidce, which live in thewater. In E
Guide to the study of insects, and a treatise on those injurious and beneficial to crops: for the use of colleges, farm-schools, and agriculturists . re thus very serviceable to the aoricul- » C* turist, as they must annually destroy immense numbers of cat-erpillars. In Europe over 2,000 species of this family havebeen described, and it is probable that we have an equal num-ber of species in America ; G-erstaecker estimates that thereare 4,000 to 5,000 known species. The Ichneumons also prey on certain Coleoptera and Hymen-optera, and even on larvae of Phryganidce, which live in thewater. In Europe, Pimpla Fairmairii is parasitic on a holosericea, according to Laboulbc-ne. Bohemanstates that P. ovivora lives on a spider, and species of Pimplaand Hemiteles were also found in a nest of spiders, according toGravenhorst. Bonche says that Pimpla rufata devours, duringwinter and spring, the eggs of Aranea cliadema, and Ratzburggives a list of fourteen species of Ichneumons parasitic onspiders, belonging to the genera Pimpla, Pezomachns, Ptero-malus, Cryptus, Hemiteles, Microgaster, and Mesochorus. 1JI4 Emerton informs me that he has reared a 1ezomachus fromthe egg-sac of Attus, whose eggs it undoubtedly devours. Theyure not even free from attacks of members of their own family,us some smaller species are well known to prey on the cut off from communication with the external world,the Ichneumon larva breathes by means of the two principal trachea?, whichterminate in theend of the body,and are placed,according to Ger-st aecker, in com-munication with astigma of its the com-plete assimilationof the liquid food.,**£• l-:{- the intestine ends in a cul de s«c, as we have seen it in the larva? of Humble-beesand of Stylops, and as probably occurs in most other larva?of similar habits, such as young gall-flies, weevils, etc., whichlive in cells and do not eat solid food. The first subfamily, the Ecanii(ht\ are insects
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Keywords: ., bookcentury1800, bookdecade1870, bookpublishe, booksubjectinsects
