The somewhat elongated prothorax is connected to the propodeum (the first abdominal segment) by a very long petiole, and the ventral side of the hind femur bears teeth.

[1] S. serrator is known from Spain, France, Netherlands, Italy, Germany, Switzerland, Austria, Czech Republic, Hungary, Romania, Bulgaria, Croatia, Serbia and Montenegro.

[1] Adults can be found on and around trees that have been dead for about a year and which contain beetle larvae, but which have not yet been invaded by fungi; this wasp has been recorded parasitising several different host species.

Other non-natural habitats where it has been observed include fencing, utility poles, wooden boarding and stacked firewood, in each case attracted by beetle larvae within.

Female wasps that are trying to locate beetle larvae in wood adopt a characteristic posture with fore and hind legs spread widely, middle legs folded tightly against the body, antennae lowered and ovipositor sheath pressed against the wood; they then move a few centimetres to a new location and repeat the process.