Erigone atra

Difficult to distinguish from congeneric species due to similar size and coloration. Diagnostic features include the 2-2-2-1 tibial spine pattern, specific eye arrangement, and examination of pedipalp structure. Females closely resemble Erigone arctica; males closely resemble Erigone dentipalpis. Examination of genitalia may be required for definitive identification.

Primarily inhabits grasslands, fallows, and crop fields, particularly cereal fields. Prefers perennial grasslands with high vegetation yield and low species diversity. Uses sown weed strips in cereal fields as overwintering sites. In winter, occupies higher vegetation habitats for protection and insulation. Found in grazing lands where combined cattle and sheep grazing creates uniform short grass expanses.

Holarctic distribution. Most abundant in Western Europe. Recorded from North America, Europe (including Russia from European region to Far East), Central Asia, China, Mongolia, Korea, and Japan.

Two generations per year. First generation from overwintered adults produces offspring maturing in early summer. Second generation matures in early fall. Some females overwinter fertilized, storing sperm for spring egg production. Peak activity in warm periods of early summer and fall.

Preys primarily on aphids (Aphididae) and isotomidae springtails. Also consumes gnats and other small crop pests. Prey selection varies by habitat and is size-dependent; females show minor preference for larger springtails and have higher predation rates than males.

Development highly temperature-dependent. At 20°C, reaches adulthood in approximately 20 days; at 10°C, development averages 150 days; at 5°C, molts only once. Two generations annually with partial overlap. Females produce multiple egg sacs throughout adult life, averaging 4.4–11.8 eggs daily at optimal temperatures. Clutch size averages 12–14 eggs, decreasing with female age. Females typically die within 10 days of producing final egg sac. Lifespan sexually dimorphic: females live on average 18 days longer than males. Egg sacs parasitized by Gelis festinans, a specialized ichneumonid wasp.

Exhibits extensive aerial dispersal via ballooning, initiated by tip-toeing behavior where spiders climb to elevated positions, raise abdomens, and release silk threads to catch air and electric currents. Ballooning cues include wind turbulence, food deprivation, and temperature increases, with mass dispersal in late summer triggered by high temperatures. Also performs short-distance rappelling using silk for controlled bridging. Captures prey both by web entanglement and active hunting; adult males hunt almost exclusively without webs. Builds small sheet webs (median 7.6 cm² in crop fields) over ground depressions or bare soil as bases for ambush hunting.

Important predator in agricultural ecosystems, contributing to biological control of crop pests. Functions as a source population in cereal field systems, colonizing crops from perennial grassland refugia. Serves as host for specialized parasitoid Gelis festinans. Its ballooning dispersal enables rapid colonization of disturbed habitats and agricultural fields.

Valued as a biological control agent in agriculture due to predation on aphids and other crop pests. Its presence in cereal fields and grasslands contributes to integrated pest management. Agricultural practices such as combined grazing and maintenance of perennial grassland strips can enhance populations.

• Erigone arcticaFemales very similar in appearance; requires careful examination for differentiation
• Erigone dentipalpisMales very similar in appearance; pedipalp structure may be needed for identification
• Lepthyphantes tenuisSympatric linyphiid in agricultural habitats; silk not recognized by E. atra parasitoid Gelis festinans, suggesting chemical differences
• Bathyphantes gracilisSympatric linyphiid with similar habitat use; silk not recognized by G. festinans
• Oedothorax retususSympatric congener in agricultural fields; silk not recognized by G. festinans
• Oedothorax fuscusSympatric congener; silk not recognized by G. festinans

• spider
• agricultural pest control
• aerial dispersal
• ballooning
• sheet web
• biological control
• holarctic

• BugGuide
• Wikipedia
• iNaturalist taxon
• NCBI Taxonomy
• Catalogue of Life
• What a Wasp! What a Tattoo! | Bug Squad
• Bug Eric: Caught on Video: Prionyx atratus
• T.G.I.Flyday—Black horse fly (Tabanus atratus) | Beetles In The Bush
• Three new species of ground snakes discovered under graveyards and churches in Ecuador
• Lymexylidae | Beetles In The Bush
• Multiple Megarhyssa males | Beetles In The Bush
• Environmental and genetic background of tiptoe-initiating behaviour in the dwarfspider Erigone atra
• Observations on the life cycle of Erigone atra (Araneae, Erigoninae) in a heavily grazed pasture
• Sown weed strips in cereal fields: overwintering site and “source” habitat for Oedothorax apicatus (Blackwall) and Erigone atra (Blackwall) (Araneae: Erigonidae)
• Host location by Gelis festinans, an eggsac parasitoid of the linyphiid spider Erigone atra