ENTOMOLOGICAL SOCIETY OF FRANCE. 125 



many instances of analogy to circunnstances attending the re- 

 production of Aphides at a certain period of the year. The 

 female Coccus, whose abdomen is vastly distended, produces 

 successively hundreds of little ones, which proceed from her 

 body, not as eggs but, as hexapod and very active insects. 

 At the time of their birth the young are excessively small, and 

 of a bright red colour: they soon scatter themselves over the 

 surface of the Nopal, and after having chosen a convenient 

 place, they fix themselves, and acquire in time the size of little 

 peas. It is, however, the females only that acquire this size, 

 and it is these alone that are an article of commerce. The 

 males are exceedingly different in form ; they possess wings, 

 which the females are entirely without ; and their size is so 

 diminutive that for a long time they totally escaped obser- 

 vation. Indeed in their adult state they scarcely attain the 

 size possessed by the females at the time of their birth : 

 measured with nicety, they are a millemeter in length, whilst 

 the females measure a centimeter. Their body is red, without 

 any down, and their wings are semi-transparent, and covered 

 with a kind of whitish powder. About the time of coition 

 these are very active, and wander incessantly over the surface 

 of the Nopal : their activity is increased by exposure to the 

 sun's rays : the males are at this moment particularly abun- 

 dant in the conservatories of the Museum, and a great number 

 of young females are observable in the act of plunging their 

 beaks into the stalks of the Nopal, in order to fix themselves. 

 Ail the females, even the smallest, are covered with an abun- 

 dant cottony down, which is a secretion from the surface of 

 the skin, and which I have made my particular study." 



M. AuDouiN then explained the economy of the larva of 

 an insect which forms galleries in the shoots of the pear-tree ; 

 and he exhibited to the Society the stem of an espalier- 

 pear-tree, aged four or five years, which he had obtained 

 from a large garden in the Rue de Varrenes, under the 

 management of M. Derviliers. This skilful horticulturist hav- 

 ing observed many pear-trees with longitudinal fissures in the 

 bark, — which, although they appeared superficial, and injurious 

 to the bark only, yet were a certain indication of disease, and 

 rarely failed to cause the death of the tree, — consulted M. 

 Audouin as to the cause of this phenomenon. The investi- 

 gation he had made speedily convinced him that this malady, 



