The effect of conspecifics on the timing of orb construction in a colonialspider

Meteperia incrassata (EO. Pickard-Cambridge 1903) (Araneae, Araneidae) are colonial spiders that share a common and relatively permanent framework of silk, but that construct and defend individual orbs within the communal fra mework. Orbs are taken down nightly and replaced in the morning. Larger spi ders generally begin orb construction before smaller spiders do. We tested whether this pattern results from interactions among spiders of different s ize classes. We constructed artificial colonies that contained either a mix ture of size classes or a single size class. In two replicates, spiders tha t were housed in single-size groups built their orbs at the same time as th eir counterparts in mixed groups. We suggest that conspecific interaction i s unlikely to be the only factor determining the differences in the timing of orb construction among size classes in this species.