of dominants. Sexually selected signals in males Males of P. dominula use their physical features to sexually appeal to the females and copulate. They have a pair of yellow dorsal abdominal spots that act as sexually selected signals. The size, location, and coloration of the spots also determine the males' hierarchy, mating success (being preferred/rejected by females) and victory in male-male competition. Females preferred males with smaller, more regular spots. Similarly, those "preferred" males were more likely to be the dominant males in the population by winning more same-sex fights, compared to those with larger, irregularly shaped spots. Visual signals of status and rival assessments Black facial patterns are associated with the male P. dominula dominance and conditions. Facial patterns of the male P. dominula vary from being "unbroken" to "scattered" – an unbroken black spot represents "low quality" while scattered spots (having several spots) represent "high quality". Males generally avoid fighting with "high quality" males and fight for resources that "low quality" males are protecting to reduce the cost of aggressive competition. Naturally, such behaviors give rise to social hierarchy, placing males with more spots on top of the social class. Similar to the abdominal spots that imply strong fighting fitness and mating success in male P. dominula, the salient patterns on the female's clypeus demonstrate strong correlation to its dominance and is used to facilitate rival assessments. Dufour's gland secretion The use of cuticular hydrocarbons (CHCs) in recognizing nest mates and neighbors is a relatively well-known method for Hymenoptera, especially among Polistes. However, Dufour's gland secretion has also been discovered to contribute in such assessments of invaders and nest mates. Chemical analysis of the Dufour's gland secretion revealed that it has a very similar composition as the cuticular hydrocarbons. However, a big difference was that cuticular hydrocarbons had more linear hydrocarbons than the glands and dimethylalkanes were more prevalent in gland secretions. Significantly different dimethylalkanes were found in foundresses belonging to different colonies, suggesting that these could be used to discriminate species of different origins. Roles of cuticular hydrocarbons in larvae Because the chemicals coated on the nests are equivalent to that present in adult P. dominula bodies, young wasps learn this chemical template in the very early state of the adult life to later on be able to distinguish their nest mates from non-nest mates. The CHC composition of the larvae and adults are very different, in