INSECTS AFFECTING PARK AND WOODLAND TREES 639 



Willow cone gall 



Rhabdophaga strobiloides Walsh 



A peculiar conelike deformity on the tips of willow shoots is due to the work of this 

 insect. 



These interesting galls are rather common objects about Albany, and 

 the insect presumably has a wide distribution in the United States, though 

 specific records of its occurrence are not abundant. 



Description The gall, a tapering, conelike, terminal growth, is 

 obviously a mass of aborted leaves, one overlapping the other much as the 

 scales of a pine cone. This deformity was figured by Glover in 1874, m 

 addition to the description and illustrations given by Walsh, who also 

 figured the adult fly without describing it. 



Life history. The parent insects, according to Walsh, appear in April 

 or early May, and the gall commences its growth shortly after and attains 

 full size by the middle of June. In its early stages it is spherical and 

 enveloped in a dense mass of foliage, which gradually falls off toward 

 autumn, and by November the twig 

 on which it occurs, if small, is killed 

 at the tip. At this time the larva is 

 in the heart of the gall inclosed in a 

 delicate membranous cocoon, where 

 it remains till the following spring, 

 when it transforms to the pupa and 

 shortly after the fly escapes. 



Witch-hazel cone gall 



HormapJiis hamamelidis Fitch 

 Conical, green or reddish galls occur 

 in considerable numbers on the upper sur- 

 face of witch-hazel leaves. 



Though this remarkable plant Fig. 171 Hormaphis hamamelidis: tf=ealls, natural size 



^=section of gall, much enlarged. 'After Pergande, V . S. 



louse was briefly described by Dr A Rr ic. dw. Ent. Tech. s er . 9 , iqoo 



Asa Fitch in 1851, very little was known concerning the species till it was 



