nests collapsing. At this point, further foundresses would be forced to build their nests in harder soils where the nests could be built closer together without compromising nest architecture. Foundresses may test the hardness of the soil by biting into the surface or performing a short test dig. Temperature Nest temperature determines egg development and foraging active time of females. As long as temperatures do not reach lethal thresholds, developmental rates of offspring will increase with temperature. Higher temperatures will also increase the thoracic temperature and allow females to fly more rapidly. With increased speed in flight, females are allowed more time for foraging, mating, and excavating nests. Most nests of H. rubicundus are south facing and sloped because of this desire for increased temperature in nesting sites. Based on the distribution of this species, facing the south maximizes the period of time sunlight is shining directly on the nest. Sloping substrates increase the surface area of the nest and allow for higher absorption of sunlight. In order to test the temperature of the substrate, females often spend several seconds basking at various points on the ground while searching for nesting sites. Soil water content The water content of the substrate in which foundresses build the nest is important, as waterlogging must be avoided by using well-drained soils, which provides another advantage to building in sloping ground. However, there must be an adequate moisture level to prevent desiccation of the brood cells. Soil samples taken near the nests of H. rubicundus demonstrate a relatively high humidity. Parasites Halictus rubicundus nests are attacked by kleptoparasitic bees (e.g., Sphecodes), as well as flies (Bombyliidae, Anthomyiidae). Although it would seem as though nesting in dense groups would draw attention to aggregations and increase mortality by parasitism, such is not observed to be the case; because the sweat bees nest densely, it is assumed that there is a large dilution effect that proportionally decreases mortality rates by parasites. Colony cycle and demographics H. rubicundus’s annual colony cycle is dependent both on hibernation and mating schedules. After hibernation during the winter, female foundresses who mated the previous cycle emerge in the spring. They each create their own nests in late spring, where they rear a single brood. Females are more likely to build nests where there is a warmer surface temperature, as this indicates a warmer interior of the nest for the offspring to develop