626 NEW YORK STATE MUSEUM 



Oak leaf bullet gall 



Dryopliaiita polita Bass. 



A small, globular gall occurs in numbers in August and September on both surfaces 

 of the leaves of scrub and post oak. 



This gall ranges from about ^ to 34 inch in diameter, is at first pale 

 green but sunlight changes it to red or reddish brown. It is found on the 

 foliage of young and thrifty shoots, from one to 20 occurring on a leaf. 

 When dry the shell is very thin and brittle and contains a round larval cell 

 held in a central position by radiating branching fibers which extend to 

 the outer shell. The perfect insect becomes matured in October and 

 remains in the gall over winter. 



Oak fig gall 

 Biorhiza fortiioniis Walsh 

 Irregular reddish tinted, greenish galls occur in dense clusters along the midrib of 

 the leaves or on the stems of white and scrub oaks in midsummer. 



This species is rather common, and was met with at Karner on the 

 dwarf chestnut oak, O u e r c u s p r i n o i d e s, being quite abundant in lim- 

 ited localities. The galls on the young twigs and leaves are very pretty 

 about the middle of August, being irregular in shape, greenish yellow and 

 tinted with red. Plate 48, figure i, represents a mass of forming galls 

 and shows the badly infested shoots as well as the foliage. The galls are 

 found along the midrib on both the upper and under surface. The old 

 galls, as they appear on the dead twig are represented at plate 48, figure 

 2. It will be seen that they constitute a very irregular mass and look 

 not unlike figs closely packed around a central stem. The gall flies emerge 

 from small circular holes. This species was met with by Dr Fitch on 

 thrifty growing white oaks, on which tree he stated it is quite abundant. 

 His description of the formation of the galls is as follows : 



I he female pierces the bark with her ovipositor, and inserts a number 

 of eggs at a short distance from each other, apparently sinking them into 

 the wood beneath the bark causing a little discoloration and a spongy spot 

 runs inward from the gall to the pith of the limb. These wounds of the 

 bark heal over so that no indication of their presence can be detected with 

 a magnifying glass. A little smooth round swelling or elevation on the 

 bark soon commences above the ^%'S,, increases in size, till at length the bark 



