THE TARANTULAS 121 



they rush back into the safety of their tunnel at the slightest dis- 

 turbance. Rarely do they live in regions of dense forest or heavy 

 undergrowth, preferring open areas on hillsides, mixed desert 

 growth, or the fringe of cultivated lands. The burrow usually has 

 a loose webbing at the entrance (Plate XVI), spun there after the 

 night's hunt and indicating that the spider is at home. During the 

 winter months the opening may be plugged with silk, leaves, and 

 soil, and, in some instances, a little mound of earth surmounts it. 



All spiders need water, and tarantulas are no exception. Indeed, 

 Baerg attributes the complete disapperance of a large colony of 

 Mexican tarantulas near Tlahualilo, Durango, to a drop in the normal 

 rainfall from nine to three inches. On the other hand, small quan- 

 tities of water poured into the burrow will often bring the spider 

 rushing out into the open a procedure that affords an easy means 

 of collecting them. The tarantulas in the damp rain forests of the 

 American tropics frequently live above the ground, and after heavy 

 rains may be seen wandering around in the open. Aversion for 

 water may well have inspired some of these creatures to become 

 arboreal, and thus escape regular deluges that they might have ex- 

 perienced on the ground or below the surface. 



Tarantula burrows (Plate XVI) are often tunnels under large 

 stones. Within spacious confines the mother spider spins a tremen- 

 dous sheet, upon which she deposits her large eggs. She then covers 

 them over with a second silken sheet and binds the edges together 

 to form a flabby bag. For six or seven weeks she watches over this 

 sac, occasionally bringing it to the entrance of the burrow to warm 

 it in the direct sunlight, until finally the babies emerge. The spider- 

 lings are gregarious, and they often remain in the burrow for some 

 time after emergence; eventually they disperse by walking out of 

 the hole and moving in all directions. Since they are much too large 

 to balloon away on silken lines, they settle down in the general 

 neighborhood of the burrow, hiding under chips and stones for a 

 time and then occupying tiny burrows in the ground. As with all 

 spiders, there is a tremendous mortality in the young stages: from 

 each sac perhaps only a pair of tarantulas reach maturity. 



Adulthood for the spiderlings is very far in the future, since ten 

 years are usually required for either sex to become sexually mature. 

 The females and the immature males live in similar burrows in the 

 ground, remaining virtually indistinguishable until the last molt, at 

 which time some are surprisingly revealed as males. Many a large 

 spider of this group has been kept in a cage for years, known by 



