1977 ] 
Robinson & Valerio — Salticid Spiders 
5 
alarm pheromone, found the end of the dragline, but were unable 
to descend the thread. The spider returned to the branch and re- 
peated the operation several times during the period of observa- 
tion. (It is worth noting that at night we frequently find salticids 
and other diurnal non-web-building spiders suspended on their 
draglines beneath the vegetation. This may provide the safest 
way of spending the hours of darkness, since they are virtually 
isolated from the vegetation on which prowl innumerable preda- 
tory arthropods. Should any of these be capable of descending 
the dragline, the vibrations thereby induced would presumably 
alert the resting spider.) 
Attacks on web-building spiders. 
There are indications that web-building spiders are preyed 
upon by an extensive array of predators although the records 
are scattered throughout the literature and detailed observations 
are surprisingly few in number. Bristowe (1941; 331-443) deals 
comprehensively with the enemies of spiders in general and also 
describes a wide variety of anti-predator adaptations that spiders 
possess. The defenses of tropical orb-weavers are reviewed by 
Robinson & Robinson (1970; 649-653) and these authors describe 
particular defensive structures or behaviors elsewhere (1973a, 
1973b). Tolbert (1975) has reviewed some of the available litera- 
ture on araneid defensive behaviors in conjunction with an experi- 
mental study of the defensive responses of Argiope aurantia and 
A. trifasciata. 
Records of attacks on orb-weavers by other spiders have been 
few in number. Bristowe (1941; 377-378) lists a number of at- 
tacks on web-building spiders by hunting spiders, and, in par- 
ticular, by the salticid Linus fimbiatus. The spiders attacked in- 
cluded at least one araneid. Bristowe (ibid; 378) implies that the 
spiders were captured in their webs, “The Linus ... sat in its vic- 
tim’s web to eat the owner”. Tolbert (1975) mentions attacks on 
Argiope aurantia and A. trifasciata by salticids and states that 
attacks in the field can be induced by prodding the Argiope to 
move (Tolbert, in litt.). Enders (1974) reports attacks on orb- 
weavers by orb-weavers and (1975; 970) on the “invasion” of the 
webs of orb-weavers by errant salticids. 
In three months (May-July, 1976) during extensive census- 
ing of webs in a number of forest fringe habitats in the Summit 
