MONOGRAPH OF THE NORTH AMERICAN PHOCTOTRYPIDiE. 17 



on trees badly infested with lepidoiJterous leaf ndleis smd minerH. 

 Other genera t"re<iuent fungi, wliile iVoni recent observations ant nests 

 and their vieinity are good fiehls for some raie species in otiier genera. 



As a rub , 1b>\vers Tire U'ss frequi'ntly visited by tlie tiny species of 

 tliis faujily than in the other hynienopterons families, e\cei>t those 

 tiowers that all'ord protection or thml for their hosts. Various platy- 

 gasterius are the only luenibers of the family that I can recall having 

 captured on llowers, and in sui^h cas<*s the flowers were invariably in- 

 fested with cecidomyiid larva-, on which they were parasitic. 



When cai)tured, as with other llynieiKtptera, some pnM-totrypidsgive 

 off a waspy or pungent odor. I'rof. Westwood has recorded the 

 fact, taken from Mr. Saunders's MS. notes, that the female Scleroderma 

 linearis, taken in a house September liS, l.Sl'J, stinging his neck, wken 

 captured "thrc^w out a pungent IVetid odor." 



UIMORPIIISM AND PARTIIENOOENESIS. 



There is scarcely any doubt but that many of the wingless forms 

 to be found in various genera of this family are only dimorphic forms 

 of winged species, although comparatively little is positively known 

 on the subject. Until such forms are bred from generation to genera- 

 tion, however, as has been done in the Cynipida' by Dr. 11. Adler, we 

 must be content to describe these forms as distinct species, for any 

 other course would be unscientitic or guesswork. In this monograph 

 I have not hesitated, therefore, to give these apterous individuals a 

 separate siMJcitic name. Doubtless also, as in the Blastophagie, or tig- 

 insects, trimorphism occurs. 



Prof. Westwood,' la speaking of the genus Scleroderma says: 



Some of the spt^cies of this genus exhibit a remarkable instance of dimorphism 

 and even trimorphism in the females, some of which are furnished with certain of 

 the characteristics of the opposite sex. Sir S. S. Saunders, in addition to the ordi- 

 nary female of -S. ephippmm destitute of wings and ocelli, found one agreeing in the 

 general form of the body with the females, but possessing the fully developed wings 

 and ocelli of the male. Remembering the diversity in the size of the heads of dif- 

 ferent individuals among some of the species of ants, I was curious to ascertain how 

 far this character was to be found in these different individuals. Their heads were, 

 therefore, drawn of a large size by the camera lucida, which was then carefully re- 

 duced by measurement, when it appeared that the heads of the normal females were 

 slightly longer than wide, whereas the head of the winged and ocellated females 

 was considerably broader than long, although its length agreed very nearly with 

 that of the normal female. Their relative proportions may be expressed by the fol- 

 lowing figures : 



Long. Wide, 



Uoad of normal fep ale without winga or ocelli 



Head of female wit h wuigfl and ocelli 



' Trans. Ent. Soc. Lend., 1881, p. 120. 

 21989— No. 45 2 



77 

 78 



75 

 90 



