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slightly flattened, with short, thick legs (Fig. 1C). This allows it to 
move about freely in narrow spaces. 
The web of Filistata has strong threads of smooth silk along 
which are festooned masses of minute sticky loops (Fig. 2B), form- 
ing the hackled band. These loops easily entangle the appendages of 
most insects by becoming engaged in the hairs and tarsal claws of 
their legs. The hairless and spineless nature of the body and appen- 
dages of A. azureus may assist its progress through the hackled 
bands. It would seem that the absence of digging spines on the legs 
of Allochares, and the replacement of the prey in its own web are 
both dependent on the hackled band and its operation both as a 
trapping device for the spider and a protective barrier for the wasp 
larva. 
The thick straight claws of Allochares (Fig. 1A) also assist in 
smooth movement through the hackled bands. When we placed 
specimens of the pompilid Episyron conterminus posterns (Fox) in 
the cages, their progress through the webs was slow, with frequent 
stops to untangle the tarsal claws. E. conterminus , which attacks 
orb-weaving spiders (Evans and Yoshimoto 1962), has curved and 
toothed claws (Fig. IB) typical of many pompilids. F. hibernalis 
clearly recognizes the threat implied by the easy and rapid passage 
of A. azureus through its web, and vacates the web before the wasp 
has approached closely. No such escape response was evoked by E. 
conterminus. 
Larval Development and Morphology 
The development of A. azureus is rapid. The egg hatches in about 
3 days and the larva completes its development in 10-12 days at 
24° C. Figures 3B, 5 A, and 5B show larvae at 3, 5, and 8 days, 
Fig. 4. Mandible of mature larva of A. azureus. 
