1 86 DAVENPORT ACADEMY OF SCIENCES. 



of the types, or typical specimens, or their galls had been pre- 

 served in Dr. Riley's private collection, nowr forming a part 

 of the collection of Aphides of the United States National 

 Museum, besides all those discovered by me, while studying this 

 interesting group. 



After the completion of these investigations and the numerous 

 drawings by myself and Miss 1,. Sullivan, the manuscript was 

 transmitted to Dr. Dreyfus in expectation of speedy publication. 

 Unfortunately, however, it has been lying idle for these many 

 years, with little or no prospect that it ever will be published, 

 due, apparently, to financial and other troubles, which tend to 

 postpone its publication indefinitely. 



Under these circumstances and in justice to myself and in the 

 interest of Anierican students of entomology, I deem it proper to 

 have this part of our Phylloxerinae published independently of 

 Dr. Dreyfus. 



I^acking time to study as thoroughly as possible the various 

 species of this difficult though highly interesting group of plant- 

 lice, I was able to work out the complete history of but one 

 ■ species, viz. , Phylloxera perniciosa n. sp. , which may be considered 

 typical of the majority of the species inhabiting the different 

 kinds of hickory. 



All species of this group, as in many other gall-producing 

 insects, hatch and form their galls at the earliest possible moment 

 in spring, or, at about the time when the buds commence to burst 

 and the young>growth of twigs pushes out. After a leaf or section 

 of a young twig has ceased its growth, no galls can be formed. 



In accordance with this law of plapt-growth there is, as a rule, 

 but one series of gall-producing Phylloxerae each year, composed 

 of the stem-mother, the migrants and the sexual generation, the 

 latter producing eggs which remain dormant until the following 

 spring, to start a new cycle of life. According to my observations 

 there is at least one. Phylloxera deplanata n. sp., which differs 

 remarkably from the rest, since the stem-mother frequently or 

 more commonly produces no winged migrants, but directly the 

 sexual generation , as observed by me during earlier studies. How- 

 ever, dn the spring of 1902, when the galls of this species were 

 extremely abundant oii certain trees, I discovered also in a few 

 of them, besides the stem-mother and sexed individuals, a few 



