Nursery Web Spider

Pronunciation

How to pronounce Pisaurina mira: /piː.saʊˈriː.na ˈmɪ.ra/

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Summary

Pisaurina mira, or the nursery web spider, is known for its unique web-building for young, sexually cannibalistic mating habits, and its role in controlling pest populations in eastern North America.

Physical Characteristics

Pisaurina mira has a moderately high carapace and a long abdomen, typically less than twice the length of the carapace. The unique anterior row of eyes comprises four eyes arranged in a straight line, while another row of four eyes forms a U-shape. Males generally have longer legs compared to females, contributing to a greater leg length to body ratio.

Identification Tips

Distinguished by its nearly straight anterior row of eyes, unlike other species such as P. undulata and P. dubia, which have strongly recurved anterior rows. Males have a different morphology, exhibiting greater leg length.

Habitat

Fields, shrubs, and forest understory vegetation. Usually found on vegetation or at water margins across North America; particularly abundant in transitional areas between woods and fields.

Distribution

Eastern North America, ranging from New England and southern Ontario west to Minnesota and south to Texas and Florida.

Diet

Active hunter preying on small insects such as gnats and mosquitoes. They use their chelicerae to capture prey and inject venom to liquefy the internal organs for digestion.

Life Cycle

P. mira is univoltine, producing one brood of offspring per year. The female carries and guards the egg sac until it hatches, after which the spiderlings stay in the nursery web until their first molt.

Reproduction

Mating occurs from mid-June to mid-July. The male uses silk to immobilize the female's legs to minimize risk of cannibalism during copulation. The female builds a nursery web for the spiderlings.

Ecosystem Role

P. mira helps control pest populations as they prey on a variety of insects. Their presence is also linked to enhancing carbon storage by reducing grasshopper herbivory.

Economic Impact

Impacts pest populations in agricultural settings, thus influencing crop yield. Predators of tarnished plant bugs, which are pests for many cultivated crops.

Health Concerns

While venomous to its prey, P. mira's venom is unlikely to pose a medical threat to humans.

Similar Taxa

• Pisaurina undulata
• Pisaurina dubia

Misconceptions

Often mistaken for wolf spiders due to physical resemblance, but they exhibit notable differences in eye arrangement and behavior.

Tags

• Pisauridae
• Arachnid
• Spider
• Predator
• Ecosystem
• North America