[1] Natural selection has led this wasp to have a thick substance emitted from its abdominal glands that allows it to protect its nest from invasions.

Parischnogaster as a genus has been relatively unstudied; P. jacobsoni is one of the few investigated species because it has sufficient durability to live near human populations and it has demonstrated unusual resilience to pollution.

Its relatively primitive traits are key to describing the evolution of social behavior in wasps.

[4] Parischnogaster females present with shiny black or dark brown coloration, whereas males have gastral terga striped with white to mark them out during aerial patrols.

[2] Males of the species can be identified as distinct from P. nigricans serrei, their closest cousin, because of a knife-like spine in the center of the clypeus.

[5] The nests of P. jacobsoni generally reach their maximum size at 48 cells, and can house up to 6 females and 6 males, as well as a total of 33 larvae in a brood.

[2] However, P. jacobsoni generally has been found to build nests mostly in open spaces and even on or near man-made structures.

[3] Like all Stenogastrinae, wasps of P. jacobsoni prefer to nest in very humid environments in the rainforest, near streams or waterfalls, or on the surfaces of caves.

Particularly for the P. jacobsoni wasp, the reproductive capacity of the females in a colony determines the structured division of labor observed in their nests.

[6] Rarely, this division of labor is reversed and females with developed ovaries are subordinate to those with less reproductive potential.

P. jacobsoni is capable of recognizing immature broods as well, killing/eliminating the eggs and younger larvae of alien wasps selectively.

However, in addition to its conserved uses, the abdominal substance from the Dufour's gland can be used in a different context as an ant guard.

[9] In addition to its role in nest protection, the substance secreted via the Dufour's gland is vital to brood rearing as well as oviposition and self-grooming.

The contents of that gland, then, may have been naturally selected for their efficiency in defense and protection of the nest, via differential success of substances that do and do not produce ant guards.

Then, after stretching the gaster, the wasp brings it back toward her mouth and collects the eggs as they emerge, adhering them to the original secretion.

The key difference lies in the fact that during self-grooming, the secretion is spread all over the wasp's body, while when establishing the ant guard, it is not.

Major periods of activity occur in the morning (specifically for nest building) and the evening (for ant guard construction).

[9] Furthermore, while P. jacobsoni does not generally nest in clusters, associative foundations are occasionally found where a high density of wasps protects against various terrestrial predators.

If the object is small enough to be a conspecific wasp intruder, resident females will begin to buzz their wings and batter it in midair.

[7] P. jacobsoni wasps tend to be resistant to pollution, including areas heavily populated by humans.

[11] While the wasp has both the ability to sting and a functional venom apparatus, rarely does it demonstrate aggression against predators.

[11] The volatile compound in venom sacs of P. jacobsoni wasps consists of a mixture of chains of alkanes and alkenes ranging from eleven to seventeen carbons in length.

For P. jacobsoni, the venom is characterized by the major compound tridecane and by the presence of large amounts of undecane and pentadecane.

Some studies have shown that dead wasps treated with some spiroacetal compounds including those found in P. jacobsoni were less attacked by conspecifics than untreated ones.