34 AMERICAN SPIDERS 



times the bulk of those of any true spider. The young of these 

 spiders after the first true molt are quite large, 7 mm., even before 

 they have left the egg sac. It is small wonder that ballooning is not 

 a characteristic of this group of spiders. Some true spiders produce 

 a greater number of eggs during a single year, but female tarantulas 

 live several years, and in total number of eggs produced probably 

 far outdistance all spiders. 



True spiders may produce few or many eggs and may place 

 them in one or in several separate cocoons. A tiny cave spider, 

 Telema tenella, lays one egg at a time. The blind spider of Mam- 

 moth Cave in Kentucky is said to lay from 2 to 5 eggs. Among 

 the more generalized true spiders those of the family Oonopidae 

 lay few eggs, and Oonops pulcher of Europe is known to place only 

 two in a cocoon. The Peckhams state that Peckhamia picata, a small, 

 antlike spider, produces 3 eggs. They assumed that ants had few 

 enemies a supposition for which there seems to be good evidence 

 and that creatures resembling them would not have to produce so 

 many offspring to maintain their normal population. Likewise in 

 many other families, small spiders produce few simply because the 

 abdomen is too small to accommodate many eggs, each of which 

 must provide sufficient food for the growing embryo. They mul- 

 tiply their low production by maturing eggs for several distinct 

 layings. 



Medium-sized spiders produce moderate numbers of eggs. Tra- 

 chelas tranquillus, a common eastern American species often found 

 in houses, lays 30 or 40. Many small wolf spiders produce 100 or 

 even less. The common labyrinth spider, Metepeira labyrinthea, 

 spins 5 or 6 cocoons and places about 30 eggs in each. Uloborus 

 americanus also places a string of cocoons in her orb web and leaves 

 about 50 eggs in each. A species from the high mountains of Ari- 

 zona, Uloborus arizonicuSj is a social spider and spins several sacs 

 in each of which are about 60 eggs. And finally, the gregarious 

 Uloborus republicanus of the American tropics, somewhat larger 

 in size than the other two species, spins larger cocoons, in which 

 are as many as 163 eggs. The eggs of these three species are essen- 

 tially the same in size, measuring from .6 to .7 mm. 



The large orb weavers produce several hundred eggs. The 

 Peckhams state that the orange garden spider lays from 500 to 2200 

 in its cocoon, but McCook believed that 1000 was about the aver- 

 age number for the species. The cocoon of one of the large fisher 

 spiders from Oklahoma, Dolomedes triton, contained 1537 eggs in 



