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Skinner, Ernest B. (ed.) / Transactions of the Wisconsin Academy of Sciences, Arts and Letters
volume XV, Part I (1904)

Vorhies, Charles T.
Habits and anatomy of the larva of the caddis fly, Platyphylax designatus, Walker,   pp. [108]-123 PDF (5.1 MB)


Page [108]


HABITS AND ANATOMY OF THE LARVA OF THE
  CADDIS-FLY, PLATYPHYLAX DESIGNATUS, WALKER.
                        C. T. VORHIES.
   The larvae of the caddis-fly, I1latyphylax designatus Walk.,
fare found in great nilLibers in a certain group of ceid springs
on the southern shore of Lake AVingra, near Madison, Wisconsin.
There are several other large springs about the shores of the
same lake, but the larvae are not abundant in any of the others l
and in some are not found at all. The conditions found in the
group inhabited by the larvae are as follows: cold water in
abundance throughout the year at a temperature of 80 C. never
freezing in the most severe winter weather: plenty of clean
rather fine sand, with numerous coarser particles; many larger
stones, under which the larvae lie hidden during the daytime,;
Water-cress, Nasturtium Officinale, in great quantities, and some
water-milfoil, Myriophyllum, on which plants the larvae feed.
  A few larvae may be found during the day under the denser
clusters of water-cress, where there is little light, but not much
evidence of feeding by day may be seen. As the loose stories
under which the larvae a-re hidden are often at a distance of
five or six feet or even more from the food plant, and as the in-
testine is always found distended with food in these specimens,
the conclusion is at once forced upon us that they feed almost
entirely at night. The fact that during the day the larvae in
dishes in the laboratory cluster in the darkest shelter obtainable
lends support to this conclusion. When a loose stone is lifted
under which dozens of larvae are gathered, what at first appears
to be a mass of sand begins to heave and niove and soon resolves
itself into a number of individual larval cases, each being labori-
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