Thomisus onustus is a crab spider species in the genus Thomisus belonging to the family Thomisidae.
It has a Palearctic distribution from Great Britain and Portugal in the West to Japan in the East. It is present in most countries of Europe, but it is absent in Iceland, Ireland, Norway, Denmark and Finland. North-south distribution extends from Sweden to South Africa and from Siberia to Central Java, including temperate and tropical ecozone.
These spiders prefer warm temperatures, forest-free areas, dry and sandy habitats with high solar radiation and dry grasslands. source