ANDRICUS SOLITARIUS. 103 



Yellowish-ferrugineous ; the pro- and mesonotum more or less, the 

 scutellar f ovese and the centre of the median segment blackish ; the vertex 

 and pleurse sometimes infuscated ; the basal joints of the antennae pale 

 yellow, the apical infuscated ; legs pale yellow, the base of coxse and 

 sometimes the hind tibia3 and tarsi infuscated ; wings distinctly smoky, 

 especially before the cubitus. Head and thorax with the pubescence 

 close, short, and white ; the third abdominal segment impunctate ; the 

 second covered with a whitish pubescence to the apex ; ventral sheath 

 three times longer than broad. Head and thorax shagreened, opaque. 



Length 2|— 3 mm. 



Hartig and Schenck describe the body as being 

 entirely ferrugineous-red ; but this is certainly not the 

 case with the specimens I have bred, these having the 

 head and thorax infuscated. 



From corticis, Sieboldii, and radicis it may be 

 known by the third abdominal segment not being 

 punctured, and the head and thorax not being so 

 thickly haired ; from fecundatrix and globuli by the 

 head and thorax not being black. 



A gall well marked from its being thickly covered 

 with ferrugineous hair. It is found either issuing 

 from a terminal bud or from a lateral one along with a 

 developed leaf, the gall in the latter case being placed 

 above the leaf. It is spindle-shaped, pointed, and 

 narrowed at the apex, this terminal point being some- 

 times curved and bare or nearly so. When in the 

 axillary bud the gall at the base is bordered by small 

 bracts. It is woody and hard in texture, and contains 

 one large larval chamber. When young it is green, 

 but soon becomes ferrugineous or reddish- brown. 



Length about 7 mm. 



It is found from July to August, and becomes ripe 

 in September. When the galls have been a long time 

 in the twigs the pubescence gets completely rubbed 

 off, its colour then being dark brown. 



The only flies I have myself obtained were some 

 which I cut out dead from the galls in the spring ; but 

 how long they were dead I am unable to say. Mayr 

 gives September as the time in which the flies emerge ; 

 if so, it may be concluded it may have a bisexual 

 generation. May that be Andricus amenti ? Beyer- 



