Insect Carpenters and Masons 



By Kdwaid I"', liiyclow 



THE NDimi; naturalist who lies face 

 downward at tlic brookside, and 

 with shaded eyes watches the busy 

 life that there has its being, will see, in 

 many places, little masses of small 

 stones or bundles of small sticks, moving 

 on the bottom of ciuiet pools as though 

 they were alive. When out of the watiT 

 they seem to be only groups of stones or 

 clusters of sticks, motionless and dead. 

 But they are the homes of living lar\ae. 

 By putting them in water or by pulling 

 them apart, a whitish habitant is 

 discovered — a larva which is a dainty 

 morsel much relished by fish. Nature 

 has provided it with an ingenious means 

 of protection. The little caddis fly larva 

 is an exemplification of the old saying 

 that "necessity is the mother of inven- 

 tion," since the little animal does not 

 always build as his ancestors built but 

 adapts himself to the circumstances of 

 a new environment and utilizes whatever 

 material may be available. In some 

 localities the cases are made of stones; 

 in others of short twigs; in still others, 

 some of the little builders and mechanics 



Little masses of 

 small stones or 

 clusters of sticks, 

 motionless and 

 dead, are the homes 

 of the caddis fly 

 larvae much rel- 

 ished by fish. 

 These tiny dwell- 

 ings actually move 

 about as if alive in 

 the water, but show 

 no signs of anima- 

 tion on dry land. 

 It is a difficult mat- 

 ter to induce the 

 larva to leave his 

 safe retreat 



bori- out the interior of a slender twig or 

 straw and use the hollow as a protection 

 against the enemy fish. 



When caddis flies are placed in small 

 atjuaria they extend the bcjdy out of the 

 Iront of the protecting case and carry 

 it as they crawl. Hut jar the receptacle 

 and the larva instantly retreats into its 

 house. It is hardly possible to pull the 

 little creature out of its case, except 

 possibly from the smooth straw. It 

 clings to its covering with peculiar 

 tenacity by means of two hooks at the 

 rear extremity of the body. So firmly 

 is it anchored to the sticks that violence 

 will not dislodge it, unless the force is 

 sufficiently great to pull the insect in two. 

 But the larva may be driven out by 

 using a tiny toothpick with a blunt end, 

 or by anything else of the kind that 

 does not terminate in a sharp point. 

 Push this into the rear of the case and 

 the little animal at once unhooks 

 himself and hastens out to find a new 

 home. 



Usually the cases are straight but 

 sometimes they are curved, and a few 

 spiral forms have 

 been found, which 

 closely resemble 

 minute snail-shells. 

 The dweller in this 

 rude retreat is a 

 tisherman who not 

 only builds a home 

 of sand but uses 

 the sand to make a 

 fimnel-shapcd trap 

 faced by a silken 

 net. The funnel is 

 directed upstream. 

 At the entrance 

 the net has almost 

 rectangular 

 meshes, often in 

 beautiful regulari- 

 ty, and appears 

 nuich like a deli- 

 cate spider wel) in 

 the water. This 

 ingenious contriv- 

 ance is placed in 



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