Other Invertebrate- Animal Study 



485 



LESSON CXIV 



Ballooning Spiders 



Leading thought — The young of many species of spiders scatter them- 

 selves Hke thistle seeds in balloons which they make of silk. 



Method — These observations should be made out of doors during some 

 warmsunny day in October. Read Nature's Craftsmen, McCook, p. 182. 



Observations — i. Look across the grass some warm sunny morning or 

 evening of early fall, and note the threads of spider silk gleaming every- 

 where, not regular webs, but single threads spun from grass stalk to grass 

 stalk, or from one object to another, until the ground seems glistening 

 with silk threads. 



2. Find a small spider on a bush, fence post, or at the top of some tall 

 grass stalk; watch it until it begins to spin out its thread. 



3. What happens to the thread as it is spun out? 



4. If the thread does not become entangled in any surrounding object 

 what happens? If the thread does become entangled, what happens? 



5. How far do you suppose a spider can travel on this silken aero- 

 plane? Why should the young spider wish to travel? 



THE WHITE CRAB-SPIDER 



Teacher's Story 



\^ — TT""^*^ HERE are certain spiders which are crablike in 

 '-^ — ^ ^ form, and their legs are so arranged that they 

 can walk more easily sidewise or backward than 

 forward. These spiders spin no webs, but lie 

 in wait for their prey. Many of them live upon 

 plants and fences and, in winter, hide in pro- 

 tected places. 



The white crab-spider is a little rascal that 

 has discovered the advantage of protective 

 coloring as a means of hiding itself from the 

 view of its victims, until too late to save them- 

 selves; the small assassin always takes on the 

 color of the flower in which it lies concealed. In the white trillium, it is 

 greenish white; while in the golden-rod its decorations are yellow. It 

 waits in the heart of the flower, or in the flower clusters, 

 until the visiting insect alights and seeks to probe for the 

 nectar; it then leaps forward and fastens its fangs into its 

 struggling victim. I have seen a crab-spider in a milkweed 

 attack a bee three times its size. This spider was white 

 with lilac or purple markings. If disturbed, the crab- 

 spider can walk off awkwardly or it may drop by a silken 

 thread. It is especially interesting, since it illustrates 

 another use for protective coloring; and also because this species seems 

 to be able to change its colors to suit its surroundings. 



<^] 



A common 

 crab-spider. 



