174 Selby on Aphides. 



Note on the Flight of Aphides, September 12th, 1853, and follow- 

 ing days. By P. J. Selby, Esq. 



On Monday the 12th, and two following days, the weather 

 being remarkably calm, with a warm, hazy atmosphere, millions 

 of winged Aphides filled the air in every direction, not only at 

 Twizell, Belford, Bamburgh, &c, but to a very wide extent, as 

 the same phenomenon was observed at Dissington, not far from 

 Newcastle, and in all probability prevailed over the whole extent 

 of the county. The Aphides during the first two days appeared 

 all of the same species, being a small greenish-black kind, such 

 as infests the peach, plum, padus, &c. On the morning of the 

 14th, upon inspecting the leaves of the peach and nectarine trees 

 in the garden at Twizell, the lower surface of every leaf was 

 found beset with winged Aphides, which had already given birth 

 to thousands of young larvae ; for upon inspecting the leaves 

 with the microscope, I found what I had at first imagined to be 

 eggs, were in reality young Aphides in an active state. Thou- 

 sands had also settled upon the leaves of the rose, padus, &c, 

 where the same rapid process of reproduction was going on. 

 From the observations I have been able to make, the whole of 

 this innumerable host were impregnated females, ready to pro- 

 duce their young the moment they alighted upon a leaf suitable 

 to the ceconomy of the species. As may be supposed, millions 

 perished without attaining the object in view; and it was a 

 curious sight to see the webs of the various spiders thickly 

 covered with the prey their meshes had entangled, producing on 

 the aggregate a rich repast to the weaver of the snare. On the 

 15th, I observed, among the myriads which scill filled the air, a 

 second species, of a lively pale-green colour, but not in such 

 numbers as the dark-coloured species. The Aphides continued 

 to appear in considerable numbers for several days afterwards, 

 whenever the air became still, warm, and moist. It may be 

 worthy of remark, that this extraordinary flight of insects was, 

 as remarked on a former occasion, contemporary with the out- 

 break of that dreadful scourge, the cholera ; this fatal endemic 

 having broken out at Newcastle with a virulence far beyond its 

 former ravages, at the time the Aphides came forth in such 

 countless myriads. This apparent connexion between this fear- 

 ful disease and the flight of the Aphides, results, I imagine, 

 from the peculiar state, whether electric or magnetic, as well as 

 the warmth, moisture, and calmness of the atmosphere ; these 

 qualities being apparently required, or at least conducing to 

 render the virus of the disease more violent and concentrated, 

 and at the same time being such as to favour the development 



