Kingdom Animalia Suborder Araneomorphae Phylum Arthropoda Order Spider | Class Arachnida Family Araneidae Rank Genus | |
Similar Metepeira, Acacesia, Pozonia, Gea, Acanthepeira | ||
Kaira is a mostly neotropical genus of orb-weaving spider with 16 described species. They occur from South America up to the southern and eastern USA.
Contents
They spin small webs from which they hang upside down and attract male moths that fly into a basket formed by their legs. They use a moth pheromone for this, which resembles the one used by the bolas spiders of the genus Mastophora. The two genera are not closely related, although they belong to the same family. Thus, the same moth-catching behavior must have evolved independently in the two genera.
All species are pale yellow-white with scattered, small, white, brown and black random spots, or in some species transverse bands. Females have a body length of about four to ten millimeters. Males are less than half the size of females and less pigmented.
Kaira specimens are uncommon in arachnologist collections, and the females of different species are difficult to separate. Females and immatures can be confused with species of the not closely related genus Pozonia.
Behavior
When a fly was put into a jar containing a K. alba, the female dropped from the underside of the lid on what seemed a single thread about 12 mm (0.47 in) long and hung there until the fly blundered into her. Then she clamped her legs around it and killed it. Instead of constructing orb webs, they construct a small trapezoidal web, containing two triangular zigzags of threads, which is remade every twenty minutes. The spider then hangs upside-down by the fourth leg on the lower and shorter parallel edge of the trapezoid, which is spread by the other legs. When a moth flies into the basket formed by the spider's legs, it is clasped and bitten, and later wrapped in araneid-like fashion. The moth is then hung from a trapeze line between the last legs of the spider, which resumes the hunting posture. As many as eight moths can be caught in this way before the spider starts feeding.
Relationships
The genus is presumably related to Aculepeira, Amazonepeira and Metepeira.