MuttkowsM—The Fauna of Lake Mendota. 401 
dota. One species, Leptocella uwarowii, is especially common, 
occuring in amazing^ numbers. Each haul of a square meter 
contains a fair number of individuals, often as many as 85 to 
100 (over 500 in two instances). 
In their general ecology the caddis-worms are more uniform 
than any other group of aquatic insects. In food habits they 
are primarily phytophagous; all of them live in shelters of 
some sort,—from those formed by a loose accumulation of ref¬ 
use to the most elaborately constructed webs and cases; all are 
water-breathers and are supplied with lateral gill-filaments or 
anal blood-gills for respiration. 
Family Hydroptilidae. 
Agraylea multipunctata Curtis; Hydroptila sp.; Ithytrichia 
clavata Morton; Orthotrichia sp.; Oxyethira sp. 
These five species of Hydroptilidae occur in Lake Mendota, 
the first three quite commonly; the last two rarely. In June 
and early July when all other caddis-worms have pupated, they 
are in their larval stage and form one of the characteristic sea¬ 
sonal complexes of the lake. 
Agraylea, Hydroptila,. and Ithytrichia are very abundant in 
the rocky areas of the lake among the Cladophora, while the 
first may be more or less generally found on the filamentous 
algae which cover the bottom and vegetation of the littoral 
area to more than three meters’ depth. 
Agraylea is distinctive because of the bean-shaped green 
case, woven from parallel algal filaments; Hydroptila has a 
case of similar shape, but made up of extremely fine sand gran¬ 
ules; while Ithytrichia makes a case of clear green secretion, 
bottle-shaped, with the wider end open. The other two spe¬ 
cies, Oxyethira and Orthotrichia, have cases which are shaped 
as a poppy seed, or like a fiat fiask, respectively. In pupation 
the caddis-worm usually merely closes the open end of the 
cases, making sure beforehand that the case is firmly attached 
to a rock or plant. Ithytrichia, however, forms a pupal case 
of two tapering ends which resembles a leech cocoon remark¬ 
ably, fastening the two ends each with two bands to the under 
side of rocks. 
In places the various species may be quite abundant. On an 
Elodea plant of about three meters stem length, including all 
26—S. A. L. 
