Bug with blue hairy apendage

Bug with blue hairy apendage

Observation - Bug with blue hairy apendage - UK and Ireland. Description: Crawling crab like across my book an insect that looked like a wingless fly! but I'm sure was some sort of Bug. What was unusual about it was the blue hairs that I at first thought it was an oviposter but I am sure looked like fine clump of hairs. It was

Crawling crab like across my book an insect that looked like a wingless fly! but I'm sure was some sort of Bug. What was unusual about it was the blue hairs that I at first thought it was an oviposter but I am sure looked like fine clump of hairs. It was about 4mm in length and quite squat and eventually jumped away.