1980] Tietjen — Sanitary Behavior of Malios gregalis 
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II Interpretation of Data 
Among the social insects, nest cleanliness occupies much of the 
workers’ efforts. In the social bees, for example, the hive is kept 
meticulously clean in a variety of ways: 1) brood cells are cleared of 
excreta and molted skins; 2) adults move to the outside of the hive to 
eliminate excreta; 3) injured larvae and pupae are eaten; 4) the dead 
are transported from the nest and 5) large debris are covered with 
propolis, thus isolating the foreign object from the nest environment. 
Such sanitary behavior by the workers retards or eliminates bacterial 
and fungal growth in the high-humidity environment of the hive 
(Morse, 1972; Wilson, 1971). 
Similar data suggest the existence of sanitary behavior in M. 
gregalis. The first-approximation model (based on the distribution of 
silk) indicated that excreta were nearly uniformly deposited over the 
surface of the web in all colonies (Fig. 4). These data suggest that M. 
gregalis exhibit little or no sanitary behavior as related to the 
deposition of excreta. The second and third-approximation models 
were based respectively on the animals’ last positions and the animals’ 
distribution over time. The latter two models indicated an inverse 
Figure 4: Relative silk densities vs. excreta for the threee excreta distribution 
models. Silk density increases from zero to nine. Unmarked bars indicate the observed 
distribution of feces for each relative silk density range. Cross-hatched bars represent 
the expected distribution based on the absolute quantity of silk within each density 
range (Model 1). Stippled bars are the expected distribution of excreta based on the 
animals’ last positions (Model 2). The dark bars represent the expected distribution of 
excreta based on continuous recording of the animals’ movements (Model 3). The 
asterisk-marked bars indicate a significant deviation from the observed excreta dis¬ 
tribution (Chi-square test, p<.01). 
