|Male Phalangium opilio|
This species can be found in a wide range of habitats, including meadows, bogs, forests, and various types of anthropogenic habitats, such as gardens, fields, hedgerows, lawns, quarries, green places in built-up areas, walls and bridges.
Females have a body length of 6–9 mm (1⁄4–3⁄8 in), males are slightly smaller at 4–7 mm (3⁄16–1⁄4 in). Males however have longer legs; the second leg is about 54 mm (2+1⁄4 in) in males and 38 mm (1+1⁄2 in) in females. Males and females are similarly coloured and marked, although males' markings tend to be less clear. The body has a three-lobed darker "saddle", usually with spots or dashes in the midline. Both sexes show many tubercules with small spikes on the anterior surface of their body.
Mitopus morio has a very similar appearance, but P. opilio can be distinguished by the two pale "denticles" (small teeth-like structures) below the anterior margin of the carapace. Males have long forward-pointing "horns" on the second segment of their chelicerae.
Phalangium opilio is normally an univoltine species and overwinters as eggs. Eggs are laid in moist areas and hatch in three- five months. The immatures undergo several molts and reach maturity in two-three months. These harvestmans usually feed on soft-bodied animals such as aphids, caterpillars, leafhoppers, beetle larvae, mites, but sometime it may scavenge on hard-bodied animals such as various arthropods.  They ares also known to feed on Helicoverpa zea eggs, and thus can act as biological pest control for soybean crops. The species is nocturnal, as is typical of opilionids.
- Tone Novak; Vesna Klokočovnik; Saša Lip ovšek Delakorda; Dušan Devetak; Franc Janželpvoč (2009). "Preferences for different substrates in Phalangium opilio (Opiliones: Phalangiidae) in natural environment" (PDF). Acta Biologica Slovenica. 52 (1): 29–35.
- Jones, Dick (1983), The Countrylife Guide to Spiders of Britain and Northern Europe, Feltham, England: Country Life Books (Hamlyn), p. 310, ISBN 978-0-600-35665-3
- Allard, Cora; Yeargan, Kenneth (September 2005). "Diel activity patterns and microspatial distribution of the harvestman Phalangium opilio (Opiliones, Phalangiidae) in soybeans". The Journal of Arachnology. 33 (3): 745–752. doi:10.1636/T04-17.1. S2CID 85825506. Retrieved 16 October 2020.
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