Polistes snelleni

Polistes snelleni, the Japanese paper wasp, is a common social wasp species in central and northern Japan. P. snelleni is also found in northern China, Korea, and the Russian Far East. Due to the different climates in these regions, P. snelleni is able to adapt to different temperatures and climatic conditions. P. snelleni is typically found in hilly or submontane areas, so they are classified in the semi-highland category. P. snelleni is in the genus Polistes, with the subgenus Polistella, a paraphyletic subgenus. P. snelleni is most closely related to Polistes stigma bernadii. It is also closely related to Polistes japonicus. P. snelleni has been studied alongside Polistes chinensis, and Polistes biglumis for comparison in worker-worker conflict, which are two other paper wasps. P. snelleni are black and yellow wasps. The queens are the biggest of the species, and the workers, young queens, and males follow. Workers typically have worn wings that distinguish them from young queens. The weight of new reproductive females (young queens) is 102 mg. Workers can be identified by white-creamy body fat. Workers that have developed ovaries are workers, but not reproductive females. The nests created by P. snelleni are made vertically. They typically consist of a single comb. The comb is fan-shaped and the pedicel is attached to the basal cell. This set up allows new cells to be added distally. The founding queen uses twigs or the surface of rock overhangs as horizontal supports for the nest. The nest petioles (stem) are perpendicular to these supports. These wasps occupy a vertical zone of 200–400 meters. P. snelleni are typically found in Japan, and sometimes in China or Korea. They prefer grassy or bushy places in temperate areas. Their nests are typically found on south facing slopes in areas filled with small trees and short weeds. These nests are hung from small trees, oftentimes larch trees, and usually hang at about 20–60 cm above the ground. They also nest in roadsides and rocky cliffs, in the spaces under overhangs. The temperature in these sites rises in the daytime because the rocks absorb heat from the sun. In northern Japan near Sapporo, nests are covered with snow until early April. About 2 weeks later, the single founding queen arrives to start the nest, falling under the category of haplometrotic foundation. The first worker in the nest emerges in early July, and all emerge within a couple of days. The workers are produced by eggs that were laid at the beginning of the nest formation. The incubation period is about 60 days for a worker. P. snelleni only has 5-15 workers in a single nest, proving to be one of the smallest in Japan. Males in P. snelleni emerge after workers, during a period of 1–2 weeks, in cells that are separated from those that produce workers. There are about 10-20 males in an average nest, which is only a bit more than the number of workers. Young queens (about 30-50) also come about during this time, in late July, in northern Japan. In central Japan, the young queens come about a month later in the middle of August. Reproductive females mate during the nesting season. These young queens are particularly aggressive. It sometimes happens that there are dwarf queens that arise in the nest, that look vaguely like workers. These emerge in late August when only a few workers remain in the nest and the food supplies have dwindled. These dwarf queens have a low chance of mating because most of the males have died. Eggs and larvae disappear in middle and later August respectively. The rate of construction of the nest begins as relatively high and then drops with the hatching of larvae. However during this time, the founding queen only constructs about one third of the total cells, and half of the cocoon spinning (10 cocoons total will be made). The queen uses pulp (paper) for construction, collected from outside the nest or by taking it from workers who have collected it. This is a forcibly action (called robbing) by the founding queen, as the workers resist this. Later, the rate of construction picks up again, in conjunction with the maturation of larvae and cocoon spinning by the founding queen. The rate then increases consistently until the sign of the first workers arrival. During this time, prior to the first workers arrival, the queen successfully constructs more cells, leading to a total construction of about 70% of the nests total cells. The superindividual stage, where workers and the queen coexist harmoniously to meet the needs of the nest, lasts only about a week. Once the workers are born, the third peak in cell construction occurs, and about 15% of the cells are produced by workers who have had a few days to rest before working. The queen lays less than 1.5 eggs per day on average. She lays eggs parallel to the construction of the cells. She may lay two eggs in the same cell, even if there are open cells—in this case, only one egg develops. However, no more than 20% of the cells are empty at a time. However, a queen does not reuse cells once an egg has occupied them.