Natural history, courtship, feeding behaviour and parasites of Theridion evexum (Araneae: Theridiidae)

Abstract

Theridion evexum constructs webs in the understory of wet middle-elevation forests in Costa Rica. The spiders construct retreats by curling a leaf and produce a mesh in front of the opening. Long, more or less vertical viscid lines extend from the mesh, and are attached to other leaves. The spiders feed on a large variety of prey (e.g. flies, beetles, earwigs, centipedes), indicating that both flying and walking arthropods are trapped in their webs. The wrapping threads have large viscid globules that rapidly disperse on the prey’s surface, forming a thin film. Adult males guard subadult females in their retreats, possibly waiting for them to moult and copulate. As part of courtship, the male places his pedipalps several times on the female’s mouthparts, then one pedipalp on her mouthparts and the other on her epigynum before insertion. Eggs were parasitised by Baeus (Scelionidae) and juveniles and subadults by Zatypota petronae (Ichneumonidae). Eggs were eaten by Argyrodes sp. (Theridiidae), and Solenopsis ants stole prey accumulated in the retreats and attacked spiderlings and older juveniles.