18 INSECT TRANSFORMATIONS. 



dried the leaf by a sponge, for in this case the imme* 

 diately excreted globules became apparent*." 



In all observations upon insects, and the other 

 minute parts of creation, it is often exceedingly dif- 

 ficult to distinguish between a cause and an effect. 

 The question of the formation of honey-dew appears 

 to us particularly liable to erroneous conclusions ; and 

 we therefore venture to mention a few circumstances 

 which seem irreconcileable with Mr. Murray's 

 ingenious theory. The hop fly {Aphis humuli) we 

 think, neither does, nor (for want of appropriate or- 

 gans) can, feed on the honey-dew ; and if it did, this 

 feeding would prove rather beneficial than otherwise 

 to the plant, by clearing it from the leaves whose re- 

 spiratory functions it obstructs. So far from feeding 

 on diseased plants, an aphis only selects the youngest 

 and most healthy shoots, into the tender juicy parts 

 of which it thrusts its beak {hausteUum) , which in 

 some species is much longer than the body, and no 

 more fitted for lapping honey-dew than the bill of 

 iEsop's crane was for eating out of a shallow plate. 

 In the experiment, tried by Mr. Murray, of wiping 

 a leaf, might not the leaf have been previously 

 wounded, perhaps, by the beak of some aphis, and 

 hence the exudation of sap, not honey-dew ? and 

 may not the circumstance of his finding the honey- 

 dew on leaves where there were no aphides be 

 accounted for on the principle that the aphides had 

 abandoned, as they always do, the parts covered 

 with their ejecta, unless these fell from insects on 

 some over-hanging branch? It is justly remarked 

 by M. Sauvages, that they are careful to eject the 

 honey-dew to a distance from where they may be 

 feeding, t. We have now in our study a plant of 

 the Cliinese chrysanthemu m {Anthcmis Artemisi<B 

 * Treatise on Atmospherical Electricity, j). 117, Loud, 1830, 

 {■ Trans. Soc. Roy. de MontpelUei. 



