Uloborus campestratus
Simon, 1893
Featherlegged Orb-weaver, Hackled Band Orb-weaver
Uloborus campestratus is a small cribellate orb-weaving spider in the Uloboridae. It is one of five Uloborus in North America, distributed from the United States to Venezuela. Like all uloborids, it lacks venom glands and subdues prey through extensive silk wrapping and constriction rather than venomous bites. The species builds small horizontal orb webs with hackled, non-sticky capture threads produced by its cribellum and fluffed using a calamistrum comb on its hind legs.
Pronunciation
How to pronounce Uloborus campestratus: /ˌjuː.loʊˈbɔːrəs kæmpˈɛstreɪtəs/
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Identification
Distinguished from other orb-weavers by cribellate silk (non-sticky, hackled threads) rather than viscid glue droplets. Separated from ecribellate orb-weavers (Araneidae, Tetragnathidae) by presence of cribellum and calamistrum. Among Uloborus , specific identification requires examination of genitalia; U. campestratus is the only species in the with documented range extending from USA through Central America to Venezuela.
Habitat
Found in diverse outdoor situations including greenhouses, culvert openings, and vegetation. Webs typically constructed in sheltered locations. Specific microhabitat preferences for U. campestratus not documented separately from .
Distribution
Geographic range extends from the United States (southern portions) through Mexico and Central America to Venezuela. Records from Mexico and USA-Venezuela span.
Diet
Feeds on small flying insects captured in orb webs. Prey size limited by spider's small stature and non-venomous capture method.
Life Cycle
Females construct small, flattened, papery sacs, usually placed near web periphery; multiple sacs may be arranged in a row. Spiderlings hatch without cribellum and calamistrum, building webs with additional and retained auxiliary spiral at hub. After second , spiderlings acquire cribellum and calamistrum, enabling 'normal' cribellate web construction.
Behavior
Builds small horizontal orb webs, often with (thickened zig-zag or linear silk band). When prey contacts web, spider wraps victim extensively in silk — observed to take approximately 10 minutes even for small prey. Constriction of silk binding compresses softer body parts and may break appendages; suspected that drying silk shrinks, tightening around prey until asphyxiation. Web construction slow: each tangled spiral segment drawn through cribellum and 'fluffed' with calamistrum, requiring hours to complete.
Ecological Role
of small insects; contributes to regulation in web-building microhabitats.
Human Relevance
Occasionally found in greenhouses and human-altered environments. Non-venomous and harmless to humans. Silk can incapacitate large insects like butterflies in enclosed exhibits, though spiders cannot consume such oversized prey.
Similar Taxa
- Hyptiotes spp. (triangle spiders)Also Uloboridae with cribellum and calamistrum, but build triangular sector webs rather than complete orbs, and use web-releasing prey capture mechanism.
- Araneidae (typical orb-weavers)Build similar orb webs but use viscid sticky silk rather than cribellate hackled threads; lack cribellum and calamistrum; possess venom glands.
- Other Uloborus speciesFour other North American (U. glomosus, U. diversus, U. americanus, U. octomaculatus) share featherlegged appearance and cribellate web structure; require genital examination for definitive identification.
More Details
Cribellate silk production
Uloborus campestratus produces cribellate silk through a multi-step process: the cribellum issues fine threads that are combed by the calamistrum into tangled, woolly strands. This hackled silk snares prey mechanically without adhesive, representing an evolutionary alternative to the viscid silk of ecribellate orb-weavers.
Venom gland absence
All Uloboridae, including U. campestratus, lack venom glands — unique among North American spider . This anatomical loss correlates with extreme prey-wrapping and constriction-based subdual.