Pirate Spider Ero aphana

Pirate Spiders are so named since they invade webs of other spiders and eat the resident and/or its captured prey. They don't build their own webs.

Left and centre above: protecting head with long legs. Right above: egg sac. Of the 4 pirate (Ero) species in the UK, this is thought to be Ero aphana (much of western, central and southern Europe including southern UK since 1970s, early summer), but E. furcata (throughout temperate Eurasia including all UK, throughout the year) and E. tuberculata (much of western and central Europe including southern England, late summer/autumn) look similar. E. aphana is some 3mm head/body length and the other two 3-4mm.

The tiny spider has disproportionately long front legs, distinctively barred and spiny. It also has a knobbly, angular abdomen unlike the rounded domes of most other spiders and has a pale cephalothorax (head) with dark markings.