Robertson — Flowers and Insects. 451 
In connection with plants having so many insect visitors it 
will be well to acknowledge the sources from which I have 
received aid. Early in my work Mr. E. T. Cresson kindly 
named my bees. Later I have determined them myself from 
descriptions, and through the kindness of Mr. Cresson have 
compared doubtful cases with the types in the collection of 
the American Entomological Society. I have worked up the 
local species of Andrenidae, and described the species which 
seemed to be new. Mr. W. H. Ashmead has kindly deter- 
mined my Chalcididae, Braconidae and Ichneumonidae, though 
many of the Chalcids were determined by Mr. L. O. 
Howard. As regards the other Hymenoptera, I am respon- 
sible for the determinations, except in the case of a few 
species determined by Mr. Wm. J. Fox. 
As regards the Diptera, Dr. S. W. Williston has identified 
most of the Bombylidae, Conopidae and Syrphidae, besides 
many other species of different families. Mr. D. W. Coquil- 
lett has determined the Empidae, etc., end Mr. C. H. T. 
Townsend most of the Tachinidae. Many Diptera I have 
lately determined for myself. Prof. G. H. French has aided 
me in the determination of Lepidoptera, Mr. P. R. Uhler and 
Mr. C. A. Hart have determined the Hemiptera. The Col- 
eoptera were determined by Mr. Hart, except a few sent to 
Mr. Samuel Henshaw. In the more important anthophilous 
groups, I make it a rule to verify all determinations made for 
me, by comparison with the descriptions, whenever these are 
accessible. 
Finally, I am indebted to Mr. Cresson for the interest he 
has always taken in the entomological part of my work, and 
to Prof. Wm. Trelease for friendly advice and kind encour- 
agement as well as aid in gaining access to literature. 
VERNONIA NOVEBORACENSIS Willd.—The stems are tall, 
and terminated by numerous heads arranged inacyme. The 
heads are discoid. The florets are purple and have tubes nine 
or ten millimetres long. Pollen is carried out on the long 
hairy styles. 
The visitors consist of long-tongued bees and flies, and 
butterflies. The flowers were observed in bloom from July 
