Report of the Commissioners . y kill is to these ichneumons, more than to any other cause whatever, that we owe our immu-nity from the ravages of destructive insects. We have found at various times, that as soon as they became abundant, the pestswere almost entirely exterminated, while, if they happened to be rare, the noxious insectsthriveil, in spite of all other checks. Some of the largest of the kind, with ovipositorsthree or four inches in length, will penetrate the thick bark of trees and fasten upon theirprey. They are extremely numerous, and I suppose every species of insect has
Report of the Commissioners . y kill is to these ichneumons, more than to any other cause whatever, that we owe our immu-nity from the ravages of destructive insects. We have found at various times, that as soon as they became abundant, the pestswere almost entirely exterminated, while, if they happened to be rare, the noxious insectsthriveil, in spite of all other checks. Some of the largest of the kind, with ovipositorsthree or four inches in length, will penetrate the thick bark of trees and fasten upon theirprey. They are extremely numerous, and I suppose every species of insect has its ownichneumon feeding upon it and keeping it down. Wasps and hornets may be looked uponas partly beneficial and partly injurious. The large black hornet, with the white face,kills a good many house-flies. THE ORDER OF DIPTERA, OR TWO-WINGED FLIES. The next order of beneficial insects is the Diplera^ or two-winged flies. The Syrphusflies, (see Figs. 16, 17) of which I have spoken several times already, belong to this Fig. 62 shows a Tachinus fly, a common parasite on caterpillars. as well as the Tachina flies. Their habits are very similar to those of the ichneumons,but while the ichneumons have four wings, these insects have only two. HABITS OF THE TWO-WINGED FLIES. Their eggs are laid in the bodies of caterpillars, which the larvae thus hatched outgradually kill. The mosquito may also be considered, in one sense, a beneficial larvae live in the water, and feed upon decaying organic matter found there. It isproV)ably of assistance in rfulucing the amount of miasma in marshy places. Some of the species belonging to the family are l}eneficial, while a largenumber are injurious. Some of the carnivorous bugs belonging to this order destroy alarge number of insects, and, among others, the Colorado beetle in its larval state THE ORDER OF NEUROPTERA—DRAGON FLIES. The lastord(rr I need refer to is the Nr,uroj)tera^ to which belong the handsome
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectagriculture, bookyear
