Flowers and insects. XII. 
CHARLES ROBERTSON. 
CLEMATIS VIRGINIANA L.—The flower, with its horizon- 
tally expanded sepals, measures about 2™ across. The flower 
clusters form large, white masses upon the shrubs upon which 
the plants climb. The flowers are dioecious. The white 
color and the easily accessible nectar attract numerous, mostly 
small, short-tongued insects. The visitors, however, are 
principally flies, three-fifths of the species being of this kind. 
An interesting comparison may be made between this plant 
and Lsopyrum biternatum, an account of which is given in the 
GAZETTE, 17: 173-5. 1892. The flowers of both species are 
white, though the Clematis is more conspicuous, and the ex- 
tent of nectar concealment is almost identical. Nevertheless, 
the species show a marked difference in the kinds of insects 
visiting them, as the following table will show: 
RO Targa pee eC ae 
a | & a 
% _ ~ 
ae | & Z a | eat ile ae 
. Za = im = =) EO < 
Hn i= Oy i+] (2) < ie a a 
BiPkl Be Ee eR EEL 
m m a = I op Bs & 
ene Cae 
ddibeg biternatum | 31 ro) 10 I I 2 5 50 
—Matis Virginiana 9 oO 6 10. 7 Il 2 55 
The difference is mainly a result of the time of blooming. 
Sopyrum, according to my observations, blooms from March 
ge May 12th, and Clematis Virginiana from July 11th 
are ni Oth. During the blooming time of the former, bees 
the “eh as abundant as during the blooming time of 
jie: er. OF the lower aculeate Hymenoptera I have never 
the ‘” My neighborhood more than six species during 
shone ie of Isopyrum, though they become more abundant 
their m oe the plant goes out of bloom; but they reach 
which Pei during the period of Clematis Virginiana, within 
=i “i I have noted I15 species flying simultaneously. 
SPecies sere um 1S exposed to a tachinid fauna of only six 
S80, while the Clematis is exposed to thirty or more 
