4 Bulletin 2: Springfield Museum. 



development of a large number of galls upon a plant is injurious to that 

 plant is evidenced by the effect of the grape phylloxera, Phylloxera viti- 

 foliae, generally known as Phylloxera vastatrix. In the eastern United 

 States, where it is native, little injury results, but when it was carried to 

 France it multiplied to such extent as to cause very great loss in the vine- 

 yards through which it spread. This is an illustration of the the greater 

 damage done by a pest in a new habitat. 



Some galls are so noticeable that they have attracted attention from 

 earliest times, but it was not until 1686 that any systematic work was 

 published upon the subject, when Malpighi issued "De gallis," whilfc gave 

 descriptions of those known in Sicily and Italy. 



Among modern European writers Adler's name is especially note- 

 worthy because he established the theory, advanced by Bassett, of the 

 alternation of generations among certain of the Cynipidae. Bassett was 

 able to verify his thought in one case, while Adler worked out a series 

 of cases, but found that alternation of generations was not universal 

 among Cynipidae, as Bassett had thought probable. 



Howard, in Psyche, 1882, v. 3, p. 329, says :— "America may justly 

 claim the credit for the discovery of this most interesting fact of alter- 

 nation of generations among cynipids." Continuing, he says of Bassett : 

 "With Cynips q. operator he had observed the females of the vernal 

 brood ovipositing in acorn cups and producing the gall q. operatola of 

 Riley's MS. ; but he failed to rear the flies from these galls and so missed 

 the complete proof. In the case of C. q. batatus Bass., he had bred the 

 sexual forms from leaf galls, and the agamic females from twig galls; but 

 had not actually observed the females of the former in the act of oviposit- 

 ing in the twigs, thus again missing the proof. Riley, however, as he, 

 tells us in his published note, succeeded in breeding the agamic females of 

 (/. operator from the acorn galls, thus, in connection with Bassett's obser- 

 vation of the oviposition, completely establishing the fact of alternation. 

 So the credit should be joint." 



Much was contributed to our knowledge of galls by Osten Sacken, 

 Bassett, Fitch, Harris, Shinier, Riley and Walsh among the earlier workers 

 in America. 



While several names should be noted among recent workers, Pergande, 

 by patient observation of the gall-makers upon the witch hazel, has dis- 

 closed the identity of two sets of insects previously supposed to be four 

 species, and established the fact of their migration from one host-plant to 

 another and buck again. And Cook has given us the results of careful 

 study of the abnormal development of the plant tissues and their cell- 

 changes under the stimulus of the gall maker. 



Galls have been collected in this section which owe their origin to six 

 orders : 



Acarina (Family, Eriophyidae). 



