The amount of red, brown and yellow markings shows great individual variation.

[3] To distinguish this species from P. algidus the observer needs to examine the spines on the front tarsi of females and the inner margin of the eyes, P. interruptus females have four weak spines on the front tarsi in females and parallel inner eye margins while P. algidus has three strong spines and shows convergent inner eye margins.

[4] In California female Poecilopompilus interruptus have been collected on extrafloral nectaries of Gossypium hirsutum and both sexes captured at extrafloral nectaries of Helianthus annuus.

Flowers visited include Chrysothamnus sp., Medicago sativa, Psilostrophe cooperi, Wislizenia refracta, Eriogonum fasciculatum, Eriogonum thomasii, Ribes aureum, Acacia angustissima and Penstemon rydbergii.

There is some evidence that females feed on occasion on haemolymph of captured spiders (Evans and Yoshimoto, 1962).