Xylomyid Flies or Wood Soldier Flies is a family of flies associated with dead or dying wood.  They are rather slender wasp-like flies, 5-15 mm long, more or less brightly colored or with distinct pale markings against a black or blackish background, clothed with only inconspicuous hairs and never with bristles. The abdomen is fairly slender, oval or parallel-sided.  There are 11 species in two genera in North America.  They are found in wooded areas and the larvae are predaceous or saprophagous (feeding on dead or dying plant material).