1944] 
Caddis Flies and Pitcher Plants 
179 
CADDIS FLIES (TRICHOPTERA) AND 
PITCHER PLANTS 
By Lorus J. Milne and Margery J. Milne 
University of Pennsylvania and Beaver College 
Do caddis worms ever live in the leaf pitchers of pitcher 
plants? Is the microhabitat formed by the water in a pitcher 
plant leaf suitable for the larval stages of Trichoptera? This 
question is opened by the discovery of cases, adults and living 
eggs of Trichoptera in leaves of the pitcher plant, Sarracenia 
purpurea. 
During casual inspection of pitcher plant leaf contents, larval 
cases obviously of trichopterous origin were discovered in late 
July at Robinson’s Lake, near Irondale (Haliburton County), 
Ontario, Canada, by the writers. This is a hilltop lake, lying in 
a rocky depression, fed by rains and emptied by evaporation 
or by overflow if the level rises sufficiently to reach the low rim. 
The margins of the lake are largely boggy, where Sphagnum 
has built a floating web enmeshing waterlogged stumps, half 
rotted trunks and on which grows a dense mass of laurel and 
cranberry, with round-leaved sundew and pitcher plants in 
clumps at intervals. The water of the lake is very dark coffee 
colored, and the bottom is a tangle of waterlogged branches 
from trees. 
The first cases discovered were in dead, closed pitchers at 
the base of plants at least eight inches above lake level. The 
cases were dry and empty. The writers immediately postulated 
that the caddis worms must have crawled into the pitchers at 
some time when the lake was, say, ten inches higher and the 
pitchers were flooded. At the time of observation, however, the 
lake was unusually high from recent, frequent and heavy rains. 
It was doubted by natives that the lake had been as high since 
the past spring, when the ice and snow broke up. Since the 
depth was greater than usual, the margin of the lake, where 
shallow enough for the bottom to be inspected through the dark 
colored water, was not the “normal” lake area, and the com- 
plete lack of visible life there (including caddis cases) was not 
