Entomological Society. 9383 



larva, does not undergo what is conventionally called a complete transformation ; it 

 is quite different with the male, which after the first modification experiences a com- 

 plete metamorphosis. As soon as the female has adhered to a leaf, plunging into it its 

 sucker and its filamentous appendages, she provokes in the nutritive functions of the 

 plant a disturbance which is the more manifest as the vegetation is less active. Thus, 

 as I have said above, the best remedy will be that which reaches the larva, or at least 

 the female, before the latter is closely fastened to the plant upon which she has 

 established herself. 



" The Male. — The larva from which the male proceeds is not distinguishable from 

 that of the female on its exit from the cottony down which forms the mother's nest. 

 The similitude of all the young ones has always appeared to me to be perfect up to 

 the moment when the fall of the antennae and of the tail indicated the beginning of 

 the modifications which the insect was about to undergo. In this stage, the male larva 

 is denoted by the slightly brown coloration which it puts on, and the rigidity which 

 contracts its teguments. Whilst the female grows rapidly, preserving for a long time 

 its primitive white colour and its transparency, the male seems to progress less 

 quickly, and in some days becomes hard and blackish. It is then found fixed at 

 intervals on the leaves, looking like a dot whose very decided colour at once reveals its 

 presence. Examined with the microscope, it exhibits the structure already described 

 as that of the female, but the whole of its tegumentary envelope is nothing more than 

 a shell, which harbours in its median part a small gelatinous and transparent body, 

 whose rings, head and tail recall the larva of the Lepidoptera ; this is the larva of the 

 male ' louse,' which soon veils itself (se voile), increases in consistency, becomes of a 

 deep brown and changes to the nymph. When the male has undergone its meta- 

 morphosis, it pierces the shell and emerges from it by a hole contrived about the centre 

 of the envelope. It is a very small winged insect, H millimetre long, of thin and 

 elegant form, with rapid and abrupt movements; its body is of a beautiful metallic 

 black, its thorax has a large green disk, and its wings present brilliant red and violet 

 reflexions when the light of a lens is projected obliquely upon them. Its head is 

 adorned with facetted eyes, and with two antennae, which are relatively long and stout, 

 formed of seven joints. It has three pairs of feet, whose tarsi are surmounted by a sort 

 of slender spur. The tarsi are formed of five joints, and the first of these joints is as 

 long as the four others taken together. Its wings, which are membranous throughout 

 their whole extent, are four in number, and overlap each other laterally. The wings 

 of the first pair are much larger than those of the second pair, which they overlie on 

 all sides. The posterior part of the abdomen presents an orifice with whitish edges, 

 and by the side of it is found a retractile projection surrounded by some long and rigid 

 hairs. This little insect ordinarily remains on the plant where the females have fastened 

 themselves, and uses its wings only to skip short distances. Scarcely has it quitted 

 the shell in which its metamorphosis has been produced than it runs rapidly over the 

 leaves which bear the females, and, passing them in review successively, approaches 

 each of them, performing each time regular and uniform movements. With head 

 erect, wings half spread, and abdomen bent down behind, he hastily mounts the back 

 of the first female he meets, and after stopping there an instant, he faces about, and 

 with equal ardour rushes upon each of the females who may be nigh. The number of 

 males is much less than that of females ; I believe that the males do not form more 

 than the tenth part of a whole brood. 



" The characters enumerated above induce me to arrange this insect in the order 



