190 AMERICAN SPIDERS AND THEIR SPINNINGWORK. 



the fact tliat it is small and dark colored, this species has ahsolutely 

 nothing to protect it but the resemblance which it bears to an ant. Can 

 this alone give the species so great advantage that it is able to maintain 

 itself with as low a birth rate as three or four in a season ? Considering 

 the direct relation between mortality and multiplication, it is plain that 

 no species could maintain itself at a low birth rate were not its mortality 

 correspondingly low. It must then either practically have no enemies, 

 or its means of protection from enemies must be uncommonly efficacious. ^ 

 I state this theory without giving assent to it, and add the simple 

 remark that this species, or an Eastern species which greatly resembles 

 it in mimicry of ant forms, makes a cocoon of precisely the 

 Mimicry gj^i^^g cliaracter and protected in the same way as that of Phi- 

 Pertilitv ^^ipP^i^ morsitans, one of the most fei'tile species among tlie At- 

 tidaj. Undoubtedly, cocoons of one species are exposed to the 

 same dangers as those of the other. M^'hatever advantage, therefore, Syn- 

 agales possesses in the way of protection is limited to the mature form, 

 and does not accrue to the eggs. 



VI. 



We come now to speak of the character of maternal solicitude as 

 shown by female spiders in the vigil of their cocoons. It is beyond 

 doubt that many species do guard their egg sacs with more or 

 _^. ., less constancy during the period of hatching. The term "brood- 



ing " has been applied to this action, but, of course, is inexact, 

 and onlj' implies that the mother remains near or sometimes roosts upon 

 the cocoon, and, it is inferred, exercises some sort of protection against 

 the numerous enemies which assail the eggs. 



Mrs. Treat 2 has observed that Epeira cinerea broods her cocoons for 

 a couple of weeks, and then drops dead from her maternal watch. Cer- 

 tainly she has good occasion for thus mounting guard, for of several 

 cocoons received from that lady, every one was infested by parasitic ich- 

 neumons, whose white pupa cases occupied portions of the egg padding. 

 I have never observed an orbweaving spider in what I could consider 

 an actual state of brooding her egg nest, althougli I have sometimes seen 

 female Orbweavers clinging to cocoons apparently lately made. This po- 

 sition seems to me to be rather due to indisposition to leave the vicinity 

 after the exhausting task of spinning and enswathing her eggs. But 

 various observers attribute the habit of brooding to some of the 

 Epeiroids of England. So, also, Menge, speaking of the egg nest of 

 Epeira diademata, says that the spider literally guards it with her life. 

 It is spun under a horizontal stem beneath the bark of trees, or under 



'■ "Observations on Sexual Selection," page 74, sq. 

 ' Communication to the author. 



