Aphytis mytilaspidis occurs in Europe and much of Asia, in South Africa, North America, Mexico, Argentina and Chile.

[3] In Serbia this species is an ectoparasitoid of Epidiaspis leperii, an armoured scale insect found on fruit trees.

[4] Aphytis mytilaspidis is a solitary wasp whose life history is closely linked to its host scale insects.

Although Lepidosaphes ulmi seems to be the preferred host in New Zealand, this wasp has been reported as being the most common parasitoid attacking Quadraspidiotus ostreaeformis.

[6] Aphytis mytilaspidis was introduced into Mauritius in 1983 in an attempt to control Melanaspis glomerata on sugar cane but did not become established.