MONOGRAPH OF THE NORTH AMERICAN PROCTOTRYPID^. 17 



on trees badly infested with lepidopterons leaf-rollers and miners. 

 Otlier genera frequent fungi, while from recent observations ant nests 

 and their vicinity are good fields for some rare species in other genera. 



As a rule, flowers are less frequently visited by the tiny species of 

 this family than in the other hymenopterous families, except those 

 flowers that aftbrd i)rotection or food for their hosts. Various platy- 

 gasterids are the only members of the family that 1 can recall having 

 captured on flowers, and in such cases the flowers were invariably in- 

 fested with cecidomyiid larvae, on which they Mere parasitic. 



When captured, as with other Hymenoptera, some proctotrypids give 

 off a waspy or pungent odor. Prof. Westwood has recorded the 

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

 linearis, taken in a house September 25, 1849, stinging his neck, when 

 captured "threw out a pungent foetid odor." 



DIMORPHISM AND PARTIIENOaENESIS. 



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 iu the (Jynipida' by Dr. II. Adler, we 

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

 other course would be unscientific or guesswork. In this monograph 

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

 separate sijecific name. Doubtless also, as in the Blastoj)haga3, or tig- 

 iusects, trimorphism occurs. 



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



Some of the species of this genus exhibit a remarkabhi 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 ordit 

 nary fema^lcof .S'. ephippkim destitute of wings and ocelli, found one agreeing in the 

 general form t)f the body with the females, but possessing the fully developed wings 

 and ocelli of the male. Remembering the diversity iu 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 fouud in these diiferent individunls. Their heads Avere, 

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

 duced by lueasurcuieut, when it apjieared that the heads of the normal females were 

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

 was considerably broader than loug, altliough its length agreed very nearly with 

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

 lowing figures: 



Long. 



Wide. 



Head of normal female without wings or ocelli. 

 Head of female with wings and ocelli 



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



21989— No. 45 2 



