622 



NEW YORK STATE MUSEUM 



W ool sower 



Andricus seminator Harris 



A delicate white, pinkish marked woolly growth, from i to i '2 inches in diameter 

 encircles in June the small twigs of white oak. 



This abnormal growth is one of the most beautiful things in nature 



when in its prime. The delicate creamy white color is admirably set off 



by blotches of bright pinkish red, and the unexpected weight of the woolly 



mass only adds to our appreciation. This beautiful gall is a common 



species in New York State, and specimens are frequently sent to the 



entomologist with inquiry as to its source and character. As the gall ages, 



the white becomes a light brown and the pink a somewhat dark brown, and 



examination of its structure shows that it is composed of numerous small 



seedlike cells with the spaces between filled by a soft hairlike growth. 



Each of the seedlike bodies contains an insect and from a specimen 



received in 1898, 235 adults were reared. The flies appear in June or early 



„ July. The operation of egg laying has been described by Dr Harris 



substantially as follows. He states that the female lays a great number of 



eggs in ringlike clusters around small twigs of white oaks, and that her 



punctures are followed by the growth of a rough or shaggy reddish gall, 



sometimes as large as a walnut. Dr Fitch states that the growth from the 



eggs laid by the midsummer flies forms a harder and more woolly gall, of a 



coarser texture and duller color, and that it resembles a ball of wool. 



These remain through the winter, though their attachment to the twig is so 



slight that birds often tear them off. The gall is illustrated on plate 49, 



figure 1. 



The adult fly has been described by Dr Harris as 1 lo inch long, almost 

 black or of the color of pitch, highly polished, except on the abdomen, with 

 the mouth parts and legs a cinnamon color. Dr Fitch states that the 

 female may be distinguished by its longer abdomen and its being black. 



Woolly oak gall. . Indricus operator Osten Sacken. This gall closely 

 resembles the beautiful structure produced by the wool sower, A n d r i c u s 



