It is an obligatory social parasite, unable to feed itself or look after the colony and reliant on ants of another species, Formica, to undertake these tasks.

[2] P. mexicanus was one of these, a widely distributed species found in western North American and originally described by the Swiss myrmecologist Auguste Forel in 1899, the type locality being Mexico.

This species also bears longer brownish macrosetae (hairs) but they often get worn away, leaving dark scars on the tergites.

A newly mated female of P. mexicanus enters the nest of a potential host, employing pheromones to subdue the resident workers.

These then proceed to rear her brood as well as maintaining the nest and feeding the dulotic queen and the ants which develop from the eggs she lays.

They then surge inside and quickly begin to emerge carrying host pupae, prepupae and sometimes late-stage larvae back to the dulotic nest.