1937] 
Case-building Instinct of Trichoptera 
125 
OBSERVATIONS AND EXPERIMENTS ON THE 
CASE-BUILDING INSTINCT OF TWO 
SPECIES OF TRICHOPTERA 
By Manton Copeland and Sears Crowell 
Searles Biological Laboratory, Bowdoin College, 
Brunswick, Maine 
The observations recorded here concern the case-building 
activities of two species of caddis fly larvse. The first of 
these belongs to the Limnephilidse, the other is a species of 
Molanna. Our interest in studying the case-building of 
these animals has centered around the experimental modifi- 
cation of the process, and we have endeavored to determine 
the extent to which this instinctive activity may be altered 
or adapted to changed conditions. Dembowski (1933) has 
made a very careful study of the case-building of Molanna, 
regarding this process as significant in indicating the 
plasticity of an animal’s actions. Many papers on the case- 
building of caddis flies are to be found, but no others with 
this viewpoint. (See bibliography of Betten, Lloyd, or 
Greene and Milne.) Although our experimental work awaits 
completion, it has seemed proper to publish those observa- 
tions which are believed to be new and which may be of 
assistance to others who are studying animal behavior or the 
natural history of the Trichoptera. 1 The various materials 
which these animals are able to use in the construction of 
the cases are described, as well as a few experiments in 
which there was an opportunity for the animals to use more 
than one kind of material, or to select the more appropriate 
one. The early steps in the formation of the cases are de- 
scribed in some detail. We believe no complete account of 
these has been published for any caddis fly larva except 
Molanna. This is unfortunate since this part of the process 
is the most difficult, and we have observed a greater differ- 
ence 1933 several authors have published comprehensive papers 
on Trichoptera as shown in the bibliography. In fact it was largely 
through the interest of one of these, Mr. Milne, that we undertook the 
publication of these observations made by us in 1930. 
