The V. arenaria queen was able to heat her nest shortly after it was constructed, and expended up to 550 cal per hour per gram of biomass to accomplish this. In contrast, the V. maculata colony was not heated until it was 11 days old, by which time the brood consisted of about 15–20 large larvae which probably played a major role in the heat production process. When both colonies were about 2 weeks old, energy expenditures of more than 400 cal/h could be maintained for several hours, and the nest temperature could be elevated as much as 4°C above the ambient. During these periods the larvae probably accounted for as much as 66–71% of this energy expenditure. In addition to playing an active role in heating the nest, the larvae apparently provide the queen with a food source while she is producing heat during non-foraging periods.