Other Invertebrate Animal-Study 



487 



HOW THE SPIDER MOTHERS TAKE CARE OF THEIR EGGS 



Teacher's Story 



ROTECTING her eggs from the vicissitudes of 

 the weather seems to be the spider mother's 

 chief care; though at the same time and by 

 the same means, she protects them from the 

 attacks of predacious insects. Many of the 

 species make silken egg-sacs, which are often 

 elaborate in construction, and are carefully 

 placed in protected situations. 



Often a little silvery disk may be seen 

 attached to a stone in a field. It resembles a 

 circular lichen on the stone, but if it is examined 

 it is found to consist of an upper, very smooth, 

 waterproof coat, while below is a soft, downy 

 nest, completely enfolding the spider's eggs. 



The egg-sacs of the cobweb weavers are 



often found suspended in their webs. One of the large orbweavers makes 

 a very remarkable nest, which it attaches to the branches of weeds or 

 shrubs. This sac is about as large as a hickory nut, and opens like a vase 

 at the top. It is very securely suspended by many strong threads of silk, 

 so that the blasts of winter cannot tear it loose. The outside is shining 

 and waterproof, while inside it has a fit lining for a spiderling cradle. 



Dr. Burt G. Wilder studied the development of the inmates of one of 

 these nests by cutting open different nests at different periods of the 

 winter. In the autumn, the nest contained five hundred or more eggs. 

 These eggs hatched in early winter but it seemed foreordained that some 

 of the little spiders were born for food for their stronger brethren. They 

 seemed resigned to their fate, for when one of these victims was seized by 

 its cannibalistic brother, it curled up 

 its legs and submitted meekly. The 

 result of this process was that, out of 

 the five hundred little spiders hatched 

 from the eggs, only a few healthy and 

 apparently happy young spiders 

 emerged from the nest in the spring, 

 sustained by the nourishment afforded 



them by their own family, and fitted for their life in the outside world. 

 Some spiders make a nest for their eggs within folded leaves, and some 

 build them in crevices of rocks and boards. 



The running spiders, which are the large ones found under stones, 

 make globular egg-sacs; the mother spider drags after her this egg-sac 

 attached to her spinnerets ; the young, when they hatch, climb upon their 

 mother's back, and there remain for a time. 



A wolf-spider carrying her egg-sac. 



LESSON CXVI 

 THE NESTS OF SPIDERS 



Leading thought The spider mothers have many interesting ways of 

 protecting their eggs, which they envelop in silken sacs and place in 

 safety. 



