Abstract
To study the kleptoparasitic behavior of web spiders invading webs abandoned by adult female Metleucauge kompirensis (Araneae: Tetragnathidae), I investigated the numbers of prey insects and intruding spiders on host webs. Tetragnatha praedonia (3.0-9.0mm long) and M. kompirensis spiderlings (1.0-1.5mm long) invaded the host-absent webs in early morning. The number of insects in abandoned webs decreased rapidly in the morning because of theft by intruders. The number of intruders increased gradually as time progressed, and in the afternoon most of them constructed small webs inside the abandoned webs. Larger intruders often drove smaller ones away, and acquired more insects than the latter. Prey theft in unoccupied host webs may be an effective strategy to obtain prey, because these webs are not defended.
