108 



THE AMERICAN ENTOMOLOGIST. 



-Black. 



It makes its appearance in the winged state in 

 September, and early in tiie following sum- 

 mer the green and shining hollow gall, with its 

 skin as thin as tjiat of a capsicum, may be dis- 

 covered almost full grown upon cottonwoods, 

 and occasionally upon balsam poplars. At this 

 l)eriod there is always found a single wingless 

 Plant-louse inside it, which has by her sole ex- 

 ertions caused the growth of the gall, and which 

 will subsequently give birth inside it to a very 

 large and flourishing family of young Plant- 

 lice, all of which will eventually acquire wings 

 and leave the gall in the ensuing September. 



TiiK Sumac-gall (liliois, Fitch), Fig. »9.— 

 This tomato-like gall occurs on the leaves both of 

 the Smooth Sumac (lihiis (jlnhra) and the Stag- 

 liorn Sumac (Blius tiipliinu), and in the States 

 both of Illinois and New York. Like the preced- 

 ing, its shell or skin is quite thin, and the 

 winged flies arc found inside it in prodigious 

 [Fife'. SO.) 



(nloi- — Givi'iii-sh yt'Uow, with a rosy 



numbers in September. Early in the spring, as 

 we have been informed by Dr. "\Vm. Manlius 

 Smith, of Manlius, N. Y., each gall contains but 

 a single wingless mother-louse in company 

 with numerous larvae. The winged fly has the 

 veins of its wings arranged in the same pattern 

 as those of the preceding species (Fig. 88), but 

 differs in having four-jointed instead of six- 

 jointed antenna'. It is also a very much sra.aller 

 insect. 



It is remarkable that there are two Chinese, 

 one .Japanese, and one Indian gall, growing 

 upon different species of exotic Sumacs, and ap- 

 parently analogous in their structure to our 

 American Sumac-gall. They are described as 



being, some of them like a radish-pod, some 

 like an ox-horn and over two inches long, and 

 some branched like a stag's horn. One of these 

 Chinese Sumac-galls, which is not uncommonly 

 to be met with in drug stores, is shaped much 

 like ours, but has a much tougher and thicker 

 rind. On breaking a specimen open, we found 

 it to be filled with infinite numbers of plant lice, 

 having wings exactly like those of our insect, 

 being of the very same size, and apparently be- 

 longing to the very same genus. Thus we sec, 

 that even on the opposite sides of the globe, 

 analogous galls are made on analogous plants by 

 analogous insects.* 



The Cockscomb Elm-oall {Ulmicola, Fitch), 

 Fig. 00. — This species has a much thicker and 

 more fleshy rind than the two preceding. 

 Young "White Elms often have their leaves so 

 densely covered by these galls that you can 

 searcelv see the leaf for the galls. After trees 



I'olor — (irccii, ofk'liwitli ;i nci rlu-i k 



get to be about twenty-five feet high the gall- 

 making insect ceases to trouble them; and the 

 younger the trees the more apt the\' are to be 

 infested. The Plant-louse that produces these 

 galls is exceedingly minute, and diflers iu the 

 veining of its wings from figure 70, c, (p. 82), in 

 the hind wing having but a single branch vein, 

 the front wings corresponding in every respect. 

 It is, however, remarkable for holding its wings, 

 when in repose, horizontally on its back, instead 

 of carrying them steeply roofed, as is tlie case 

 with almost all the other genera of Plant-lice. 

 Early in the spring but a single wingless mother- 

 louse is to be found iu a single gall ; but iu a 

 short time she gives birth to hundreds of very 

 minute and wingless young larvie. By the 

 end of June or the beginning of July, the 

 gall becomes full of winged plant lice, when the 

 slit on the under side of the leaf, through which 

 the mother plant-louse built up the gall early in 



■ flivtller details < 





