Adler found the first gall formation at the end of April in Germany, when the tips of the buds became dark blue and soon showed the form of the purple, velvety galls. Adult insects appear within a couple of weeks after the galls are mature, being recorded as emerging from May 1 to June 1 (acc. Wachtl 1876), on May 26 and early June (acc. Adler 1881) in Germany, at about the same time in Holland (acc. Beyerinck 1883), and on May 25, 29, 30, 31, and June 2, 3, 4, 6, 7, 9, and 11 in Denmark (Hoffmeyer in Kinsey coll.).
It was Adler who first observed this insect oviposit in the main veins of the not fully mature leaves of the oak—leaves which were still growing actively enough to be capable of developing new galls. Adler believed that the insects, examining the leaves with their antennae, would not oviposit in places in which galls could not have been produced. The eggs are pushed into the center of the leaf veins, one egg into each wound, but usually a total of a half dozen or more to each leaf. About a month after oviposition had been observed in 1878, Adler obtained eight folii galls from the pricked veins, establishing by these experiments the relation of taschenbergi to folii, as he later connected folii and taschenbergi. Beyerinck's results (1883) added detailed confirmation to Adler's work at this point.
Beyerinck (1883) is further to be credited for careful observations on the early development of the young gall of taschenbergi. Gall formation begins when the larva is formed but still within the egg. The first indication of the gall is an enlargement of the plant cells in the vicinity of the egg. These developing tissues, arrested where they come in contact with the egg, grow about the egg and completely envelop it. A larval cell is thus formed by the time the insect begins to show its larval segmentation but before it has emerged from the egg. The gall structure involves not only the growing tip of the young twig but the very young leaves as well, a fact that apparently explains the tiny, leaf-like irregularities that may sometimes be observed on the mature galls of taschenbergi. Beyerinck found one double gall which may have come from two eggs deposited in a single bud of the oak.
Liodora sulcata Förster (1869, Verh. Ges. Wien 19: 335) , the insect on which Förster based his genus Liodora, is con-
