2o8 botanical gazette, [ December, 



sp. 9 ; (13) P- <*$**& Sm. 9 , both f. p. Scoliidce: (14) My- 

 zine inlernipta Say ; (15) Scolia bicincla F. 



Diptera— Syrphidce: (16) Pipiza pnllchella Will. ab. ; 

 (17) Chrysogaster niiida Wied. ; (18) Syrphus ribesiiL. ; (19) 

 Mcsografta marginata Say; (20) Sphoeroph 



tip hi I a 



pipiens L., all f. p. Ephydf 





Coleoptera — Coccinellidce : (23) Megilla maculala De Ij. ; 

 (24) Hippodamea 13-pimctata L. Cei'ambycidce. (25) Ztf/- 

 iura plebeja Rand. Chrysomelidce: (26) Diabrotica 12-punc- 



tata F., ab., all f. p. 



Workers of Bombus separatus, B. americanorum 3 and B. 

 scutellaris dropped into the flowers, but immediately flew 

 away, as if they had failed to find what they sought. I also 

 found Bombus virginicus, Agapostemon radiatus and Luciha 

 cornicina dead in the flowers, where they had probably been 

 enclosed by the petals and suffocated by the heavy odor. 4 



Deniaria laciniata Muhl. — This flower agrees in most re- 

 spects with Cardamine pratensis, as described by Mtiller. But 

 the nectaries which occupy the position of the two missing sta- 

 mens are of nearly or quite the same importance as those 

 surrounding the bases of the two short stamens. Accord- 

 ingly the saccate bases of the sepals which hold the nectar 

 from these glands are of about the same size as the others. 

 The stigma commonly surpasses the anthers, so that it strikes 

 the bee in advance of them, but there is a chance ot selt-pol- 

 lination in absence of insects. 



The erect sepals and the claws of the petals measure 

 about 8 mm., and with the stamens and style narrow all ways 

 of access to the nectar, so that only insects with a tongue o 

 mm., or longer, can reach the nectar with perfect ease. But 

 short-tongued bees sometimes manage to force their way in 

 so as to reach the sweets. The flowers are white, or some- 

 times with a purplish tinge, and grow in rather conspicuous 

 umbels. There are more long-tongued bees than in Miille r s 

 list of visitors of C. pratensis. 



Visitors (observed on 7 days, between April 2 and 20) : 



s Bombus americanorum Fabr. is our common bumble bee. For a Ion i; time it has i )e ^" 

 mixed up with B. pennsylvanicus De Geer, but it is a distinct species, and B. elatus Fa ^ 

 (Apathus? elatus) is its male. I ha?e taken the sex of B. pennsylvanieus i" copu la. 

 have also taken B. elatus in copula with B. americanorum. Three nests of the latter w _ 

 I opened contained no male bees except B. elatus The nest mentioned in Proc. Ent. * 

 Phil., II, 161, said to contain 6 females and 31 workers of B. pennsylvanicus and 21 ma • 

 of Apathus elatu must have belonged to B. americanorum. 



* Delpino mentions that insects are so killed in flowers of N. speciosa. 



