Eresus kollari

Their body as most velvet spiders, resemble somewhat those in the jumping spider family. The males have a contrasting color, having a black and red coloration, while the females are completely black. The opisthosoma looks velvety, as their common name would imply.[4]

In colonies, they burrow up to 10 cm in depth. Which is usually covered in a funnel web. Females may carry lens shape egg sack containing up to 100 eggs. Which she’ll carry to a sunny place. The juveniles will stay in the females burrow and feed on her after she dies.[4] They usually form small colonies with up to a couple dozen spiders, but they may reach several hundred or more.[5]

Although they are small in size, they are able to bite. A bitten finger may cause pain, and cause fever symptoms, an increase heart rate and a headache, that last a few hours. Though it is not medically significant, and after a few days, it is mostly gone.[4]

They inhabit warm areas, in areas with loose and low vegetation. This spider most often happens in grasslands. Though it has also been found in dry and bright forests. It is found all throughout Europe, except up in the north.[5]

Some species of wasp of the family Pompilidae hunt exclusively on the Eresus genus. These wasps enter a burrow and look for the spider, and they paralyse it with strong venom. The female lays the eggs on the spider, and after a few days, the eggs hatch. These larvae eat and kill the spider.[5]