174 
Psyche 
[June 
dragline contacts during female dragline-following resulted in fol- 
lowing by males, and most imitation draglines were not followed 
the entire length. 
Male L. punctulata followed ground lines, but did not follow 
male and imitation draglines. This species appears to depend upon 
the female pheromone for initiating and for maintaining dragline- 
following. Apparently, male L. punctulata are either more sensi- 
tive to tactile input provided by ground lines, or more sensitive to 
pheromonal cues than male L. rabida, or both. 
The differential sensitivity to tactile and chemical cues exhibited 
by the two species may be related to microhabitat preferences. L. 
punctulata is found in the lower levels of the herbaceous stratum 
(Eason and Whitcomb, 1965) in which one expects a greater di- 
versity and density of spiders (Whitcomb, Exline and Hite, 1963) 
and consequently more draglines. Many lycosids of similar or 
larger size are found within this microhabitat of which male L. 
punctulata could be potential prey, including L. helluo and L. caro- 
linensis. Continuous sampling for female pheromone during drag- 
line following reduces the likelihood that males will follow another 
species’ trail in a high silk density microhabitat. In addition, due 
to the greater foliage density at this level, many draglines could be 
expected to be laid directly on a substratum. A greater sensitivity 
to tactile and/or chemical cues could allow male L. punctulata to 
follow such ground lines. 
L. rabida , on the other hand, is found high in the herbaceous 
stratum (Eason and Whitcomb, 1965; Kuenzler, 1958) and is asso- 
ciated with lower interspecific silk densities derived mainly from 
smaller species such as salticids and oxyopids. Foliage density is 
less, and a greater volume of open space is found at this level. 
Fewer female silk trails would be expected to be found directly on 
this substratum. Under these conditions the sensitivity to tactile 
and/or chemical cues exhibited by L. punctulata would not be 
required for efficient dragline-following by male L. rabida. 
Silk lines are destroyed mechanically in the field by wind and 
the activities of animals. Moisture resulting from rain and early 
morning dew inactivates the female pheromone found on unbroken 
lines (Dondale and Hegdeker, 1973; Hegdeker and Dondale, 1969). 
All of these effects reduce the likelihood that males will follow 
draglines laid the previous day. 
