the dragon-fly is a most welcome one, for then an immediate burst of cold wind is confidently looked for. In the expressive vernacular of the gauchos the large dragon-fly is called ‘_hijo del pampero_,’ son of the south-west wind.”[42] ----- Footnote 35: Vol. 57. Footnote 36: Appleton’s Popular Scientific Monthly, vol. v. Footnote 37: Buckton, Monograph of the British Cicadæ or Tettigidæ. Footnote 38: White’s Natural History of Selborne, Letter liii. p. 283 (stereotyped edition). Footnote 39: Buckton, Monograph of the British Cicadæ or Tettigidæ. Footnote 40: Leland O. Howard, The Insect Book. Footnote 41: The Entomologist’s Monthly Magazine, October, 1900. Footnote 42: Hudson, The Naturalist in La Plata, pp. 131, 32. ------------------------------------------------------------------------ CHAPTER XI Aphides and their enemies—Curious interrelations—The biter bit—Altruistic development—Bread and beer protectors—Saved by ladybirds. WITH prolific powers which have been successful in arousing the interest even of the late Professor Huxley, it is a comfort to think that the numbers of the Aphides are always being kept down by the operation of certain well-contrived causes, most of which take the shape of various insect enemies. Were all of these, or perhaps were any one of them, entirely removed, the whole world apparently might find itself deep buried beneath a “star-y-pointing pyramid” of insect organisms, for what cannot quintillions, in the hands of a competent mathematician, achieve? The wonder certainly seems that any kind of check should be sufficient. We owe our safety, in part, as might have been surmised, to a small Ichneumon Fly, the traces of whose work may generally be seen in a number of brown lifeless corpses, which are dotted about like so many skeletons at the feast, amongst any collection of living Aphides. These, if examined more closely, are seen to be mere empty sacs, each one having at some part of it a quite circular aperture, through which the issuing guest has escaped. But the amount of the good thus effected is not to be estimated by the number of these shells, these nests from which the bird has flown. Such are only in the last stage of things, whilst almost all, including the healthiest-looking of the living Aphides, are probably travelling along the same road, to arrive at the same goal. All, or almost all, have within them a guest whose energies are unceasingly devoted to absorbing the whole of their interior arrangements into itself, and gradually taking their place. “In June,” says Mr. Buckton, “during the hot weather, I have seen, at the same time, as many as three of these flies on one rose sprig, each poised on the back of an Aphis, which throws itself into many contortions for the purpose of throwing off its enemy. The Ichneumon, however, remains fixed on the back for ten or more minutes (as though enjoying the situation)