1880], 225 



It was easy with that insect, whose life-history the able President 

 of the Italian Entomological Society followed from the egg up to the 

 copulation of sexuated individuals, to describe the full cycle of life, 

 the two food-plants being known, and the entire evolution being aerian 

 on the branches or leaves of the oaks. Prof. Targioni did what I had 

 done before for PJiyll. quercns : he tied a muslin bag round the little 

 oak tree Avhich he had infested with Phylloxera, and was able in that 

 way to show to the Italian Entomological Society the whole life-cycle 

 of his PliyUoxera Signoreti. But this kind of procedure is not always 

 BO easy, because there are many gall-lice that migrate to plants yet 

 unknown to us, and, with one exception {Pemphigus spirothecce), all 

 poplar, elm, and pistacia gall-lice are in this position. 



This year I followed up with curiosity the existence of gall-lice on 

 Pist. terehinthus, a common tree in our parts, which has on it no less than 

 five very different galls, all formed by Pemphigians of various species. 

 All these galls burst in the summer, and give issue to well-known 

 winged lice, namely. Pemphigus utriculariics, cornicuJarius, semihinarius, 

 follicularius, and pallidas ; these forms are all " emigrants," and pro- 

 duce agamous rostrated young ones. 



Two months before the time when the emigrants come out of the 

 galls, while watching with care the Terehinthus trees, I saw a lot of 

 winged lice arrive, mostly by night, on the stems, and deposit their 

 little sexuated lice, which copulated; afterwards the females hid them- 

 selves in the crevices, where they died, keeping in their body the 

 solitary egg, which passes the winter, and in the ensuing spring gives 

 the gall-producing louse. I have no doubt that these winged forms 

 are the pupiferous Pseudogynes of the gall-makers on Terehinthus, but 

 none of them look like the " emigrants " which come out of the galls 

 in the autumn. 



So, although quite convinced that it is onl}- a form in the evolution 

 of the above-named Pemphigians, I am at a loss to apportion the true 

 pupiferous to its corresponding emigi'ant. 



It is also a very singular fact, that of the five different forms 

 which arrive on the stems (a number which corresponds exactly to the 

 galls on the Terehinthus) two have only five-jointed antennsB. Thus, 

 according to the actual classification of gall-lice, they do not even 

 belong to the genus Pemphigus ! yet they are certainly only a phase 

 in the biological evolution of one of the Terehinthus gall-lice. The 

 characteristics of the genus Pemphigus must therefore be changed, 

 and we must say in future : " antennse 5-jointed in the emigrant form 

 issidnq from the galls." 



