a 



NATURAL HISTORY. 



known commonly as the " American blight " (Sckizoneura lanigera), a small insect covered with ?, 

 white cotton-like secretion, often does much injury to apple-trees. Three species of Laclmus 

 are found upon the oak. Of the species haunting the leafy parts of trees, a considerable number 

 produce great deformations of the parts they attack, which grow out into gall-like or bladder-like 

 structures, within which the Aphides reside. The leaves and leaf-stalks are the parts chiefly affected 

 in this way, and the effect produced varies from a mere crinkling of the leaf to the formation 

 of a regular sac having only a narrow slit of communication with the outer world. Such structures 

 may be constantly found upon poplars and the various kinds of willows and sallows. 



The reproduction of the Aphides constitutes one of the most interesting chapters in the history 

 of the Animal Kingdom. In the late autumn, males and true oviparous females make their 

 appearance, and the latter, after fertilisation, deposit their eggs in sheltered situations, where 

 they remain until the spring. Among the progeny of these eggs there are no males, and after 

 changing their skins three or four times the insects arrive at their mature form, when they give 

 origin, asexually, to another generation also of asexual forms, and this process goes on throughout 

 the summer. These asexual forms are generally viviparous, the young being produced by a process 

 of internal budding from organs representing the ovaries of the perfect females, and they usually 

 show, at the time of their birth, the rudiments of the next generation. These asexual forms may 

 be either winged or wingless, and their production xinder favourable conditions may go on for a long 

 time. Thus Bonnet observed the production of nine, and Duvau of eleven generations, whilst Kyber, 

 by keeping a colony of Aphides in a warm room, was enabled to continue their asexual reproduction 

 for four years. This, therefore, is a very complex case of " alternation of generations," the whole of 

 the individuals produced between one asexual generation and the next having to be regarded as 

 larval forms, whether winged or apterous. It would appear, however, from recent investigations, 

 and especially from those of M. Jules Lichtenstein, that matters are not quite so simple as above 

 stated, at all events, in the case of some species observed by him, though how far his results will 

 apply to the whole family is at present a matter for further investigation. In the case of the 

 Phylloxera of the oak (Phylloxera quercus), M. Lichtenstein states that the egg, which is attached to 

 the bark of Quercus cocci/era, produces at the end of April an apterous form which he terms the 

 foundress. This changes its skin four times, and then produces asexually egg-like bodies (pstudova), 

 which it attaches to the petiole and lower surface of the leaves. These pseudova produce the first 

 larval form, which is apterous and larger than any of the succeeding forms. It gives origin to the 

 second larval form, which acquires wings and migrates in May to another species of oak (Quercus 

 pubesceiis), under the leaves of which it settles, then produces egg-like bodies, from which the third 

 larval form originates. This is apterous and viviparous, producing its like by internal gemmation, 

 and this process may be continued several times. It is this third larval form the reproduction 

 of which was observed by the writers above cited. Towards the autumn a fourth larval form 

 appears, which acquires wings and returns to the Quercus coccifera, where its progeny consists 

 of larvae which develop into sexually perfect male and female insects, which are apterous and 

 destitute of a rostrum. The females produce a single large egg. M. Lichtensteiii's observations 

 upon other species seem to show that analogous processes of reproduction prevail widely among the 

 Aphides, but how far this may be the case is at present doubtful. The whole question is one 

 of great interest, and one to the solution of which any person possessing leisure and patience might 

 easily contribute. The history of the Aphides also presents many other points of interest, and 

 the beautiful monograph of the British species by Mr. Buckton published by the Kay Society 

 will greatly facilitate its study. 



FAMILY XIX. COCCHLE. 



This family, chiefly formed by the Cochineal insects and their allies, is a curious one, and in 

 some respects differs greatly from all the other Rhynchota. The Coccidse usually have beaded 

 antennae, composed of six or more joints ; they have two-jointed tarsi ; the wings are generally 

 wanting in the females, and the hind wings in the males, which also have the rostrum suppressed. 

 The metamorphosis is peculiar. The larvae are small, tortoise-like creatures, which run about freely 

 upon the plants which they frequent. When full grown, the females without any particular change of 



