REPORT OF THE STATE EXTOMOLOGIST I907 363 



Members of this genus display a marked preference for flower 

 or bud galls, a very large proportion being reared from, de- 

 formed buds, among which may be classed the conspicuous 

 apical rosette galls, the less conspicuous flower or bud galls and 

 the reduced flower heads. A number also breed in leaf galls 

 such, for example, as R. p e d i c e 1 1 a t a and R. fusiformis, 

 both of which inhabit a very characteristic type of gall appear- 

 ing on the stem, the leaf or even in the flower head. 

 Certain species breed in bud galls near the base of the stem as, 

 for example, R. b u 1 b u 1 a , and one species, R. t h o m p s o n i, 

 in the root stock. The well known R. h i r t i p e s is unique 

 among our eastern forms, in that it produces a very character- 

 istic gall on the stem. This latter exception, however, is more 

 apparent than real, since the original point of attack is undoubt- 

 edly on the young growing stem, and it might be considered 

 as an injury just falling short of the terminal bud. The last 

 named species is easily separated from allied forms. American 

 members of this genus display a marked preference for Solidago, 

 some fourteen species having been reared therefrom, while the 

 closely allied Aster supports three additional forms. Each of 

 the species of this genus producing a gall on Solidago, makes a 

 characteristic deformity which appears to be correlated with well 

 marked structural differences in the adult, and presumably by 

 divergencies in habits. 



Key to species 



a Antennae wit'h 20 or more segments 



b 24 to 2S antennal segments ; abdomen dark reddish brown ; palpi 

 biarticulate ; female, bred from loose, rosette galls on Solidago 



canadensis Carolina n. sp., C. ai635 



bb 22 to 23 antennal segments 



c Abdomen dark brown; legs dark brown; antennal stem % 

 longer than the basal enlargement ; palpi biarticulate ; male 



major Felt, C. 90 

 cc Abdomen reddish brown or brownish red; antennal stem in 

 male ^ and in female Ys the length of the basal enlarge- 

 ment; male and female, bred from subglobular stem gall 



on Solidago 



(C e c i d o m y i a) h i r t i p e s O. S., C. aio59, ^1284 

 bbb 20 to 21 antennal segments 



c Antennal stem % longer than the basal enlargement ; abdomen 



fuscous 3'ellowish ; legs fuscuous yellowish 



d Palpi biarticulate, the basal enlargement with a length 



twice its diameter; male, bred from terminal rosette 



gall on Solidago c a p i t a t a n. sp., C. ai750 



