Drain Deimos are a type of B.O.W. featured in Resident Evil 3: Nemesis.
These six-legged creatures crawl up walls and onto the ceilings, and are able to leap great distances. Two shots with a shotgun or a single grenade will take them out. The player usually encounters them in pairs, but fortunately there is often an exploding red box nearby. Use the appropriate button to target the box. The resulting explosion will take out one or both of them.