The males have claimed their territory by rubbing sternal brushes along the border of the site, leaving a chemical that deters other individuals from approaching.
[1] M. flavitarsis feed on arthropods, nectar, and animal carcasses and are often prey to birds, ants, and praying mantis.
[1] Henri Louis Frédéric de Saussure, a Swiss mineralogist and entomologist, classified M. flavitarsis in 1854.
[1][6] M. flavitarsis is found in the western United States and Canada, ranging from southern California to British Columbia.
[1] M. flavitarsis is also known to nest in the built environment, particularly in protected spaces such as wall voids, the underside of eaves, etc.
Early emerging daughters help to construct the natal nest by building it larger and strengthening the stem from which it hangs.
[1] Foraging for the nest continues through August, and the adults that emerge at this time are typically males and non-worker females.
The nest will be abandoned by M. flavitarsis between September and November as the females begin to seek shelter for hibernation.
[3] The dominant female becomes queen and will eat the eggs of subordinates on the same day they are laid to direct reproduction.
However, after six to seven days of waiting, the male will then remain at his perch site for the rest of the 6–7 weeks of mating.
Following mating, females will walk over the surface of the perch site, dragging their abdomens, before flying off.
Following the fight, the owner returns to its perch site, and again, rubs its abdomen to secrete its scent and ward off future intruders.
When a usurper attacks, the two wasps fight by biting, using antennation, and grappling each other attempting to sting each other.
It was found that M. flavitarsis are more likely to approach the freshly damaged leaf, which release mechanical odors that serve as cues for the wasps.
[9] Male M. flavitarsis have larger sixth, seventh, and eighth sternal glands than other wasps, suggesting a role in secretion and possible sexual attractant.
[4][10] Secretion is suggested because the wasps will often rub their abdomens along the nest, spreading a highly repellant substance to deter ants.
[7] Due to the relatively cool and dry climate in which M. flavitarsis lives, it is the only species in the Mischocyttarus genus to hibernate and will seek shelter for the duration of the months of October through April.
[1] Birds such as flickers, acorn woodpeckers, Mexican jays, and flycatchers are typical predators of M. flavitarsis.
One final predator of M. flavitarsis is the praying mantis, which will eat perching males during mating season.
If the nest is in the emergence phase or later, M. flavitarsis are more likely to sting a predator or intruder as a form of altruistic suicide because of colony size.
[2] When disturbed, M. flavitarsis will stand high on their mid and hind legs with their forelegs and abdomen raised and antennae forward.