Polistes apachus is a social wasp native to western North America.

Simmons et al. reported how in California P. apachus is often found in fig orchards where it is considered a pest species due to its aggressive attacks and painful stings on farm labourers during harvest time in September and October.

[11] Polistes apachus was originally named by Henri Louis Frédéric de Saussure in 1857.

[1][12] A phylogenic study by Pickett et al. in 2006 was unable to resolve anything useful regarding the relationships of the different Polistes species amongst one another.

This may be due to two identical cryptospecies sharing the same range, simply a sampling error, or some other form of karyotypic diversity.

[14] It is classified in the subgenus Fuscopolistes according to James Michael Carpenter and Bolívar Rafael Garcete-Barrett (2005).

As with all or most Polistes species, there is no recognizable difference in size or appearance between egg-laying queens and her workers.

The penis valve is about 1/3 of the length of the apical (front) of the aedeagus and it is dilated, bi-lobed, and has a clearly distinguishable entrance in the central portion.

The lateral apodeme of the aedeagus is directed forward with a weak central projection and almost the same size as the ventral process (projection), this process being rounded and slightly expanded at the apex, but slightly constricted in the first part.

The inferior (lower) portion of the aedeagus is weakly curved -it appears almost straight when viewed from the side.

[16] The cuspis is robust, covered with short and sparse bristles, and of a triangular shape, with its apex being indistinctly pointed and tapering gradually to the end.

[16] Nests can grow to be large by the end of the season, containing about 150 cells according to Richard Mitchell Bohart and Bechtel,[6] but average nest sizes of up to 320 cells and 13cm in diameter are reported in Californian fig orchards by Ebeling, with a maximum comb size of 15X20 cm.

[1][3][17] P. apachus is the largest and most brightly-colored Polistes in the state of California, which helps with differentiate it from similar species.

According to the identification key supplied by Bohart and Bechtel, it is most similar to the other Californian Polistes species P. dorsalis[18] and P. aurifer.

[6] Polistes apachus was collected for the first time in 1856 by the Swiss scientist and wasp specialist de Saussure, who had travelled north from central Mexico into Nuevo México, a vast area spanning from modern Nevada to Texas which the United States had occupied and annexed a few years previously.

[5] Bohart and Bechtel believed the Californian population to be disjunct to the rest of the distribution in the east of Mexico and the rest of the US,[6] however this species has been collected in contiguous areas south into Baja California and eastwards in Arizona.

[1] Polistes apachus often makes its nests in vineyards and orchards, and can also be found in more urban areas.

The queen maintains her role as the only egg-laying individual, while the other fertile females are relegated to worker status.

If the dominant queen dies, however, one of the other fertile females can take over her duties to ensure the survival of the nest.

This suggests that Hamilton's theory of kin selection does not provide an adequate explanation for eusociality in P. apachus.

[22] In the wild they build their nests hanging from a branch near the tops of shrubs or small trees,[1][8] for example Baccharis sp.

[1][3][9] Many species of Polistes prey on caterpillars, which they do not eat themselves, but macerate to serve as a protein-rich juice for their larvae.

[9] One former pest control professional has recommended using a jet of high pressure water to spray them off of eaves, doing this early in the morning while the wasps are less active, quickly crushing any wet and stunned wasps which fall into the garden, and doing this in the spring before the nests become too big.

Recent studies have used venom specific detection to determine that P. apachus stings have led to anaphylaxis.