Cues Guiding Placement of the First Loop of the Sticky Spiral in Orbs of Micrathena Duodecimspinosa (Araneidae) and Leucauge mariana (Tetragnathidae)

Summary Several of the cues generally used by orb-weaving spiders to guide sticky spiral placement are missing when the spider lays the first loop of sticky spiral in an orb. This study combines behavioural observations and web measurements to suggest that two species of spiders use the distance between the outer loop of temporary spiral and the frame line to guide placement of the first loop. The correlation between these two variables occurred, however, only in a context in which spiders contacted the frame—when the outer loop of temporary spiral was near the frame. The correlation was absent when the temporary spiral-frame distance was large, and spiders generally failed to contact the frame line. The cue used to produce the correlation is thus probably sensed when the spider contacts the frame line while laying the first loop.