390 Handbook of Nature-Study 



ing. The mother caddis-flies lay their eggs in the water. Perhaps 

 some species drop the eggs in when hovering above, but in some cases 

 the insect must make a diving bell of her wings and go down into the 

 water to place her eggs securely. The wings are covered with hairs 

 and not with scales, and therefore they are better fitted for diving than 

 would be those of the moth. I have seen caddis-flies swim vigorously. 

 References Aquatic Insects, Miall ; Manual for the Study of Insects, 

 Comstock. 



A spiral ribbon caddis-worm case. The Case and caddis-worm, 



inmate of this case is a rapid swimmer. Comstock's Manual. 



Photo by J. T. Lloyd. 



LESSON LXXXV1 

 THE CADDIS-WORMS AND CADDIS-FLIES 



Leading thought The caddis-worms build around themselves little 

 houses out of bits of sticks, leaves or stones. They crawl about on the 

 bottom of the pond or stream, protected from sight, and able to withdraw 

 into their houses when attacked. The adult of the caddis-worm is a 

 winged moth-like creature which comes in numbers to the light at night. 



Method With a dip-net the caddis-worms may be captured and then 

 may be placed in the school aquarium. Duckweed and other water 

 plants should be kept growing in the aquarium. The log cabin species is 

 best for this study, because it lives in stagnant water and will therefore 

 thrive in an aquarium. 



Observations i. Where do you find the caddis-worms? Can you see 

 them easily on the bottom of the stream or pond? Why? 



2. Of what are the caddis-worm houses made? How many kinds 

 have you ever found ? How many kinds of materials can you find on one 

 case? Describe one as exactly as possible. Find an empty case and 

 describe it inside. Why is it so smooth inside? How is it made so 

 smooth? Are all the cases the same size? 



3. What does the caddis-worm do when it wLhes to walk around? 

 What is the color of the head and the two segments back of it? What is 

 the color of the body? Why is this difference of color between the head 

 and body protective? Is the caddis-worm grown fast to its case, as the 

 turtle is to its shell? 



4. Note the legs. Which is the shorter pair? How many pairs? 

 What is the use of the legs so much shorter than the others? If the 

 caddis-worm case happens to be wrong side up, how does it turn over? 



5. When it wishes to come to the surface or swim, what does the 

 caddis-worm do? When reaching far out of its case does it ever lose its 

 hold? How does it hold on? Pull the caddis-worm out of its case and 

 see the hooks at the end of the body with which it holds fast. 



6. How does the caddis-worm breathe? When it reaches far out of 

 its case, note the breathing gills. Describe them. Can you see how many 



