62 Dr. H. Schaum's Notes on the 



XIX. Notes on the Natural History o/" Aphides, translated 

 from Ratzeburg s Forstinsecten, Vol. Hi. 1844. By Dr. 



H. SCHAUM. 



[Read 6th September, 1847.] 



Sexes. — The sexes of the Aphides cannot be completely described, 

 the males being so scarce that they were never seen by Reaumur. 

 Ratzeburg saw those of one species only ; Degeer, Kaltenbach, 

 and Bouche, have observed them oftener. 



Generally the very lively males are winged, but there are also 

 apterous males. In almost all cases they are much smaller than 

 the females ; the apterous ones so much so, that the only time when 

 Kaltenbach saw them, he took at first the males, which were in 

 copulation, for young specimens on the back of their mothers. 

 They measured scarcely one-eighth of the size of the females. 

 Also the winged males are generally much smaller. A constant 

 character of this sex is, according to Kaltenbach, the deeply 

 emarginated semilunar shape of the first anal lobe. 



Metamorphosis. — It is incomplete, but differs in several points 

 from that of the other Ametahola. It does not always begin with 

 the eggs, but often with the larva state. Besides we find in the 

 same species, Pteromatabola and Ajiterometahola ; this is proved to 

 be the case in the females, although not quite so well ascertained 

 in the males. The larvae are less perfectly articulated, the joints 

 of the antennae fewer, the ocelli wanting, &c. It is surprising that 

 the apterous female j)arents, consequently imagines, have fewer 

 joints of the antennae than the winged females and larvae. It is 

 generally stated, that they cast their skin four times. 



Habits. — These soft and tender insects require a mild tempera- 

 ture, a closed place, and a luxurious vegetation. Consequently 

 they are more common in the southern countries and in gardens. 

 They prefer the underside of the leaves, and are more frequent on 

 wood than on grasses and herbs. No indigenous tree is free from 

 them ; on the birch and willow from eight to ten species are found. 

 The same species is generally confined to one particular place on 

 the tree. They are, as both Linne and Schrank knew well, 

 generally strictly monophagous. The puncture of their beak very 

 often causes no injury whatever ; in other cases, however, diseases 

 and disfigurations are produced by it, which are always the same 



