1978] Lubin, Eberhard, & Montgomery — Miagrammopes 
9 
Figure 5. Miagrammopes intempus female holding a single thread web. Note 
the loose line just anterior to the tip of leg IV(a), and leg II holding the end of the 
capture thread (b). 
action analysis of video-recording was needed to permit adequate 
analysis. Only M. simus was video-taped, using a SONY AV-3400 
videorecorder and a macro lens. The descriptions below are based 
mainly on analyses of these video-recordings. 
Stage I: Prey detection — jerking the capture thread 
When an insect was placed on the capture thread, the spider re- 
sponded by jerking the thread, The spider quickly flexed her lower 
leg I, which held the capture thread, and immediately extended it 
again. The maximum distance travelled by the tip of the leg on an 
upward jerk was 0.3 leg length (about 2.8 mm), and the quickest 
jerks were accomplished in less than 1/60 second (the time span 
of a single “frame” of the video-recording). It is tempting to think 
that jerking functions in gauging the weight or size of the prey, as 
seems to be the case in other uloborids (Eberhard 1969). Spiders 
with multiple capture threads (both M. sp. 1 and M. simus) jerked 
only the thread on which prey had been placed. 
