324 
Psyche 
[Vol. 89 
Wandering Spiders. Five families were collected, totalling 43 spi- 
ders in 8 genera. Five of these genera are common prey items of 
mud-daubers. A Xysticus sp. was discovered inhabiting an inactive 
Sceliphron nest and a female Platy cry plus undatus (De Geer) occu- 
pied a half-completed Sceliphron cell, constructed a retreat and 
positioned herself at the entrance. Species of Phidippus and Thio- 
dina climbed over nests, but did not remain on these structures. 
However, species of Dolomedes were frequently noted on the out- 
side of mud nests. They remained motionless for hours during the 
day and appeared to achieve an enhanced crypsis against the nest 
background. 
Spider Size. Seventy-six specimens belonging to genera taken as 
prey by mud-daubers were collected at the 3 sites. Of these, only 9 
exceeded the upper size range of congeners found paralyzed in wasp 
cells (Table 1). The 2 Argiope listed were also larger than conspecif- 
ics (N=3) that could not be handled (i.e., were repeatedly dropped 
after immobilization) by Sceliphron. These spiders were 15.0, 16.5, 
and 16.8 mm long respectively. Two spiders dropped by Chalybion 
were 15.3 mm \Pisaurina undulata (Keyserling)] and 14.6 mm long 
[Peucetia viridans (Hentz)]. The largest P. undulata provisioned by 
Chalybion was 1 1.8 mm (N=3), and the largest P. viridans was 13.8 
mm (N=14). Extensive data for Trypoxylon, generously provided 
by Dr. H. J. Brockmann, indicated that the heaviest of 289 Neo- 
scona provisioned by Trypoxylon during June and July weighed 
0.2400 grams. Spiders dropped by provisioning females exceed this 
weight on 12 occasions, ranging in weight from 0.2537-0.4236 g. 
(Spiders were weighed to the nearest 0.1 mg.) 
Wasp-Spider Interactions. Surprisingly, predation by mud-daubers 
on spiders living at nest sites was never observed. Brockmann (pers. 
comm.), who has spent over 3,000 hours observing wasps under 
bridges near Gainesville, has also never observed a single case of a 
wasp preying on a spider near the nesting site. Wasps repeatedly 
walked or flew within several centimeters of potential prey, display- 
ing no observable taxes or predatory movements. In 2 separate 
incidents, female Sceliphron that had strayed into webs of Tidarren 
sisyphoides (Walckenaer) freed themselves after stinging the overly 
eager spider. In neither instance did the wasp show any further 
interest in the potential prey item, although in both cases the spider 
