REPORT OF THE STATE ENTOMOLOGIST 1905 



99 



trees is more or less apparent from year to year, particularly in 

 the western part of the State. This species was unusually abund- 

 ant and destructive in the vicinity of Westfield, N. Y., stripping 

 entire trees of their leaves and devouring a considerahlc propor- 

 tion of the foliage of others. The caterpillars were so numerous 

 that late in Octoher masses of cast skins were still > evident on 

 black walnut trees. It is probable that this species is responsible 

 for serious depredations on black walnuts at Angola. Similar 

 injury to walnut trees at Stanley was reported by Mr J. Jay Barden. 



Hickory gall aphid (Phylloxera caryaecaulis Fitch ) . 

 Young galls of this species may be met with in early June. They 

 then vary from the size of a pea to that of a small marble, are 

 irregularly spheroid, being usually prolonged at the juncture with 

 the midrib or petiole, and with a more or less distinct, somewhat 

 irregular ventral orifice which is completely closed. The galls at 

 this time vary in color from pale greenish to a bright pink, those 

 attached to the mid vein of the leaves showing slightly on the upper 

 surface. Many of the structures are so near each other that they 

 fuse and each contains a central cavity with a stem-mother and 

 numerous young plant lice evidently just hatched from the egg. 

 Later these deformations become green or rosy and as they increase 

 in age the young plant lice become more abundant, so that an 

 examination during the later period of growth may show the inner 

 surface literally covered with numerous young pale green plant 

 lice, and somewhere in the cavity the much larger, stouter form of 

 the parent insect. Later the green distorted tissues die, turn black, 

 leaving an ugly shrunken mass. This gall insect is one of our 

 common species and is sometimes so abundant as to cause consider- 

 able injury to hickory trees. 



The life history of this insect, based upon our own observations 

 and those of Mr Pergande upon a closely allied species, is substan- 

 tially as follows : The green galls begin to develop with the unfold- 

 ing foliage and are caused by an abnormal growth of tissue around 

 the stem-mother, which latter hatches from a winter egg about 

 the time the young leaves appear. The increase in tissue is very 

 rapid and soon the insect is inclosed in a globular cavity. An 

 examination shows the latter to be inhabited by a single stem- 

 mother or parent insect and numerous young. The galls become 

 fully developed in the course of a few weeks and allow winged 

 individuals to escape. These latter may be observed upon all kinds 

 of vegetation in the neighborhood of the tree and eventually produce 

 the generation which deposits on the trees eggs as mentioned above. 



