Twelfth Report of the State Entomologist 291 



covered with a very fine pruinose powder, resembling mold; some hav- 

 ing small scales or rudimentary wings, showing them to be pupae ; 

 their cast skins thickly interspersed among them, resembhng white 

 meal; the larger galls with only the walls of the cavity covered, and 

 crowded with similar lice. 



Exception should be taken to Dr. Fitch's comparison of the galls to 

 " little round balls of different sizes." All that have come under my 

 observation are elongated, and decidedly pyriform in shape, as may be 

 seen in figure i of Plate XIV, which fairly represents quite a num- 

 ber of others in the state collection. It is probable, however, that 

 examples of rounded forms may at times occur, if we may judge 

 from the peculiarly shaped one (almost semi-globular) represented by 

 Walsh-Riley in the figure given by them, and reproduced by Dr. Thomas 

 in the 8th Missouri Report, and also by Dr. Packard in his " Guide to 

 the Study of Insects." 



Description of the Imago. 



Winged female, 0.06 in length, and to the end of wings o. 10 ; pale dull 

 green or yellowish-green ; head and antennae black ; base of thorax 

 blackish, and its anterior part light yellow ; legs pale ; wings hyaline, 

 but not clear and glass-like, their veins black, the third one abortive 

 nearly half its length, the stigma salt-white ; abdomen commonly thinly 

 covered on the back with fine pruinose matter, its middle rather deeper 

 green ; antennae shorter than the thorax, thread-like, four-jointed, the 

 first joint slightly the shortest, and the second joint rather the longest. 

 (Fitch.) 



Mr. Walsh has taken exception to the above description, in the 



following criticism : 



Dr. Fitch's description of the winged female of this species applies 

 only 10 immature specimens extracted from the gall. After they have 

 been out some time, the legs and the whole body, except the collar 

 which becomes very pale brown, turns to a decided black; and the 

 stigma then is not " salt- white," but pale dusky with a whitish reflection. 



Life-History and Food-Plants. 



The life-history of the species, so far as known, may be briefly sum- 

 marized as follows : The growth of the gall commences in the spring, 

 when it may be found occupied by the wingless mother louse in company 

 with her progeny in their larval stage. The occupants multiply rapidly, 

 increasing largely in number until during September, when the gall 

 matures and gives forth the colony, all becoming winged eventually. 



The same gall occurs on the Rhus glabra and the Rhus typhina. In 

 a note published in Insect Life (loc. cit.) it is stated that the galls of this 

 insect on Rhus glabra contain nearly as much tannin as the ordinary 



