Theridion dilutum
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adult female, live |
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adult male, live |
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female genitalia; epigynum |
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male genitalia; palp, lateral view |
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male genitalia; palp, ventral view |
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grape size comparison with adult spiders; male (left), female (right) |
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spiderling, live |
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spiderlings, dead; dorsal (left), ventral (right) |
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egg sac |
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egg sac with scale (cm) |
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.
