A. infuscatus occurs in Europe (including southern Britain) and North Africa, east to the Pacific.

[2] A. infuscatus is about 10 mm in length and resemble the Arachnospila wasps with which they are often found in appearance and behaviour.

The colouring of A. infuscatus is less red than orange and its wing venation also differs from all members of Arachnospila.

[2] Xerolycosa nemoralis, Alopecosa trabalis, Trochosa ruricola and Pardosa monticola spiders are recorded as prey[4][5] but A. infuscatus is also suspected to feed on other members of the families Lycosidae, Agelenidae and Thomisidae.

In the latter case, the A. infuscatus female entered the nest of its congener, destroyed the egg already on the spider and placed one of its own.