2 
Psyche 
[March 
the spider. We here report on field observations (in Panama and 
Costa Rica) that show that certain tropical salticids do attack and 
subdue prey considerably larger than themselves. Among these 
prey are large araneid spiders that are attacked on the web (but 
not across the web). In making these attacks on large prey the 
spider may utilize the technique of dropping on its dragline to 
isolate such prey from the substrate. This action allows the spider 
to safely attack other types of prey which, although small, are 
normally protected by social defenses. 
Observations 
An adult Phiale was observed in Panama, preying upon a fully 
sclerotised adult dragonfly that was at least three times as long 
as the spider. The spider was on the upper surface of a leaf about 
1.5 meters above ground level. At the time of discovery the dragon- 
fly was fluttering spasmodically but the actual capture was not 
observed. There is little doubt that the dragonfly was attacked 
after alighting on the leaf. The relative proportions of the spider 
and its prey are obvious from the photograph (Figure 1.). 
Observations in the Central Valley, Costa Rica, provide a clue 
about how small salticids may subdue large prey. An immature 
Menemerus bivittatus was seen pouncing on a large moth resting 
on a fence wire. The moth was about half as long again as the 
spider and perhaps twice as heavy. After the pounce the moth 
started beating its wings strongly and the spider immediately 
dropped, on its dragline, until it was well clear of the substrate 
(figure 2). The spider held the moth with its chelicerae and front 
legs until the prey was subdued. 
Clearly this method of “playing” the prey on the end of a line 
until envenomation occurs or the prey is exhausted, or both, is a 
strategy that could be applied to any prey item that tried to escape 
from the spider by jumping, dropping or flying off the substrate. 
The tensile strength of the dragline silk, in all probability, greatly 
exceeds the load exerted by the spider and her prey. The tenacity 
of the spider’s jaw hold may be the critical factor in such attacks. 
Dropping below the substrate on a dragline also provides the 
spider with an effective method of dealing with some species of 
ants that have social defenses. Thus some species of Pseudomyr- 
mex possess a strong alarm pheromone that directs large numbers 
