Theridion dilutum

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Current valid name

Theridion dilutum Levi (family Theridiidae)

Recognition and diagnostic features

Tiny spider, globose abdomen, light body coloration.

Related or similar species

Theridion melanurum, immatures of Latrodectus hesperus.

Spider

Body lengths when mature: male: 2.0 - 2.8 mm, female: 2.0 - 2.9 mm

Immatures resemble miniature adults.

Egg sac

Description: spherical tan papery ball, suspended in web, 2.35 ± 0.42 mm diameter

Number of eggs per sac: 29.3 ± 8.8

Size of egg: 0.53 ± 0.029 mm

Time of year eggs are likely to be laid: April through September

Distribution

In California: southern half of state

Elsewhere: southwestern U.S. and Mexico

Native to North America

This species has not been transported or become established outside of its range.

Biology

Cobweb weaving spider. Makes web in grapes leaves. Eggs can be found in grape bunches. Female guards egg sac.

Status in table grapes

Level of Incidence: very common

Level of Concern in New Zealand: WPNZ (May 2010) nr, BORIC (Dec 2011) R, MAF-BPRA (2002) nr (coding definition)

Level of Concern in Australia: WPAU (2006) nr (coding definition)

Level of Medical importance: none

Common name

None for species, combfoot spiders for family

Taxonomic history

Stable

Selected references

Levi, H. W. 1957. The spider genera Enoplognatha, Theridion, and Paidisca in America north of Mexico. Bull. Amer. Mus. Nat. Hist. 112: 1-124.