THE TARANTULAS in 



voluntarily. When forcibly removed, it will accept the unoccupied 

 tunnel of another spider, or a cavity especially made for it, and 

 proceeds to remodel this in a characteristic way to suit the pattern 

 of previous homes. 



Although spiders of many other families burrow, the trap-door 

 mygalmorphs have far outstripped them in the excellence of their 

 tunneling. They have become specialists that dig with better in- 

 struments, line with greater care, and are the originators of the 

 intriguing practice of capping the burrow with a perfect lid. While 

 this trap door is not a unique accomplishment of these spiders, 

 having been developed independently by several other groups, it 

 bespeaks a mastery not closely approached by any emulator. 



The typical burrow is spacious enough in part of its length to 

 allow the spider to reverse position at will. Within its confines the 

 spider finds a haven until violent or natural death. What are the 

 advantages of this abode, which has become such a dominant ele- 

 ment in the lives of these spiders? In the first place, it is the 

 property of a single, unsocial individual and can become, with the 

 passage of time, more and more adequately coated with silk, more 

 and more familiar in its every part, and thus increasingly acceptable 

 to the spider. It is a retreat from the rays of the sun, the extreme 

 heat of which is shunned by nocturnal and diurnal forms alike. 

 Its hinged lid, which can be opened or closed at will, prevents rain 

 and surface water from entering, thus keeping the nest drier than 

 surface situations. Since all the burrowing spiders live more than 

 a single year, the tunnel serves to temper the extremes of inclement 

 weather over long periods. The tube beneath the surface is cooler 

 during the summer heat, and somewhat warmer during the extreme 

 winter cold. Relatively inconspicuous because of its location on the 

 surface of the ground, the burrow opening may be made even more 

 difficult to discern through the efforts of the spider. During the 

 hottest part of the summer, when inimical parasitic wasps are pres- 

 ent in maximum number, the opening may be closed tightly with 

 earth and silk. Mosses, leaves, sticks, and other debris can be placed 

 to advantage on the lid and around the entrance, the result to 

 human eyes at least hinting of camouflage. When in active use, 

 the burrow can serve as an ambush from which the spider rushes 

 out to seize its prey; and once an insect is caught, the nest becomes 

 in most cases the dining room. At the proper season the burrow 

 may also serve as a mating chamber, the eggs being laid and en- 

 closed in their sac within its confines. Later it becomes the home 



