Hartslock Nature Reserve is an 11-acre (4.5 hectare) section of the much larger Hartslock SSSI near Goring-on-Thames, south Oxfordshire, England. The reserve is primarily south-facing chalk downland surrounded by thick, ancient hedges and narrow tracts of mixed yew and deciduous woodland.
The site has a very rich diversity of species characteristic of the habitat, including:
Monkey orchids (Orchis simia), Lady orchids (Orchis purpurea) and the hybrid between both species rare plants such as Bastard Toadflax (Thesium humifusum), Downy-fruited Sedge, Dodder and Slender Bedstraw Dingy Skipper (Erynnis tages), Grizzled Skipper (Pyrgus malvae) and Green Hairstreak (Callophrys rubi) butterflies Club-tailed dragonfly (Gomphus vulgatissimus) is a frequent visitor in May, flying up from the Thames Ephemera lineata, a rare mayfly also swarms in thousands on the site during the mating season Mecyna flavalis, a rare day-flying moth seen commonly in July Hartslock is open to the public throughout the year. Dogs should be kept on a lead because livestock is often kept on-site.