1972] 
Fergusson — Hypochilus thorelli 
183 
tached to a circular sheet of silk laid down on the substrate. The 
sides of the lampshade extend away from the substrate, flaring to a 
larger mouth. An extensive tangle of lines connects the lampshade 
to the surrounding substrate and serves to keep the lampshade taut. 
Sticky silk is found only in the lampshade and support lines (Shear, 
1 97 ° )• 
The web of H. thorelli (Figures 1-3) is similar to that of 1 H. 
gertschi, as described by Shear (1970). This includes (following 
Shear’s terminology)) the meshed lampshade, with 10-15 paired 
support lines attaching it to a frame line, which is guyed to the sub- 
strate and to the extensive angle of threads below the lampshade. 
H. thorelli rests with its ventral surface appressed to the substrate, 
with all legs touching the lampshade at its base (Figure 4). This is 
somewhat different from the position of H. gertschi , which holds on 
to the lampshade with its first two pairs of legs, and to the circular 
sheet with its last two pairs (Shear, 1970). 
I measured lampshade base diameter, mouth diameter, and depth 
of 10 H. thorelli webs. The range of values obtained was: base 
diameter 2.2-7. 4 cm, mouth diameter 3.3-14.2 cm, depth 1.5-9. 5 
cm. I also measured base diameter of 134 webs in an attempt to de- 
termine age classes (see Life History below). 
Comstock (1940) observed web construction behavior in H. 
thorelli. He found that the disc of silk was first laid down on the 
substrate, then the foundations of the lampshade were constructed, 
and finally the lampshade itself was completed. The only construc- 
tion activity I observed was web repair after prey-capture. The 
spider combs its cribellum silk with the calamistra on the last pair 
of legs, while applying silk to the damaged area. The edges of the 
torn area of the lampshade are pulled together with the other legs 
during this process. The spider often returns to the web base, pulls 
on the sides of the lampshade to test its tension, and then resumes 
work if the repair is not “satisfactory.” Extensive web repair, and 
probably also web construction, takes place at dusk and night; it was 
not observed during daylight. 
Predatory behavior. H. thorelli does not respond to prey in the 
tangle below the lampshade unless the impact is violent, in which 
case it reacts as it does to a threat (see Defensive Behavior). A 
prey struggling in the sticky lampshade causes the spider to test web 
tension by flexing its legs and tightening the web in order to locate 
the prey. (One very large and vigorous insect — an ichneumonid 
wasp — caused a defensive reaction when it was caught in the lamp- 
shade.) The spider than orients so that it faces the prey. Usually 
