128 METAMOEPHOSES OP MAN 



anatomical conditions^ was in opposition to this con- 

 clusion. It was known that in the earthworm and 

 the slug the intercourse of two individuals was as 

 necessary to the ends of procreation as in mammalia 

 and birds. Reaumur also, who was then universally 

 recognized as arbiter in all matters relating to Natural 

 History, was about to decide in the negative, when he 

 was suddenly left in a state of doubt by some facts 

 which he had observed when studying the plant-bugs 

 (Aphides) . 



Most of our readers are acquainted with these 

 insects in the larval stage. They are the creatures 

 which appear in thousands upon the branches of fruit- 

 trees, and the steins of flowers and of peas.* They are 



* The plant-bugs (Aphides) are insects belonging to the order 

 Hemiptera, that is t(^ say to the group which includes the Cicadidae, 

 Cimicidae (bugs), &c. They form a very extensive genus, whose 

 species are even yet far from being all known. These insects are 

 genuine parasites, living upon vegetables, and in these temperate 

 climates there is hardly a single plant but what supports its own 

 species of aphis either upon its stems or its leaves, or about its roots. 

 Many species of Aphis may be classed among the noxious insects. 

 Reaumur discovered that the punctures made by them, when in 

 sufficient quantity, not only exhausted the plants, but gave rise to 

 nodular swellings, and to alteration of the tissues. The laniger 

 plant-bug (Lachnus laniger), which attacks apple-trees especially, 

 has on many occasions destroyed the plantations of Normandy. 

 This species, which is one of the disastrous results of commercial 

 intercommunication with other countries, was found in England, 

 according to M. Tougard, in 1787. In 1812, it had reached the 

 French departments of C6tes-du-Nord, Manche, and Calvados. In 

 1818, it made its appearance in Paris in the garden of the " Ecole 

 de Pharmacie ; " it was seen in the departments of the Seine-Infe- 

 rieure, the Somme, and the Aisne in 1822. Finally, it was dis- 

 covered in Belgium in 1827. This formidable little insect has for 

 some years held its sway in the southern departments, no means of 

 destroying it having been discovered. 



