It is a ground-nesting social insect whose colony cycle lasts only one season, common throughout the northeastern United States and much of Canada.

[3] The orange-belted bumblebee forages on Rubus, goldenrods, Vaccinium, and milkweeds found throughout the colony's range.

Like many other members of the genus, Bombus ternarius exhibits complex social structure with a reproductive queen caste and a multitude of sister workers with labor such as foraging, nursing, and nest maintenance divided among the subordinates.

Workers have very little fat, particularly in their abdomen, leaving plenty of room for the honey stomach, an enlargement of the oesophagus in which nectar can be stored on foraging trips.

The coloration of the thorax and abdomen is similar to that of the females, with the exception that the last abdominal segments are yellow on the sides.

[4] B. huntii, another species of bumblebee common throughout the western United States, is nearly identical in coloration to B. ternarius, though it has primarily yellow facial hairs rather than black.

Their United States territory extends from New York and Pennsylvania to Michigan, Washington, Wyoming, Utah and Montana.

[8][9] B. ternarius, like most members of its genus, are seasonal, meaning the queen comes out of hibernation in late April to start a new colony.

The bumblebee workers fly from May to October when the entire colony dies (except hibernating queens) to start the cycle again.

[7][9] In late April, the queen comes out of hibernation from under a few inches of loose soil or leaf litter, and begins to search for a nesting site.

Bombus ternarius prefer to nest underground in small and shallow cavities like rodent burrows or natural crevices.

[9] She flies low to the ground, stopping often to investigate holes in the earth, and once a satisfactory nest site is found, she forages for pollen and nectar to support her future offspring.

[10] Next, the queen secretes a protective waxy coating and builds a grove where she lays fertilized eggs destined to be the first of the new workers.

This close contact allows the queen to incubate her brood with the heat she generates by pulsing contractions in her abdomen.

Naturally, during her absence, the brood cools rapidly, so the availability of plentiful and rewarding flowers near the nest site is vital.

[9] In late summer, the queen switches to laying unfertilized eggs, which develop into male drones that are meant for reproduction.

During this time, the new queens mate with roaming male drones, build up reserves of body fat, and fill their nectar crop with honey to survive winter hibernation.

They fly in a circuit and deposit a pheromone on prominent places such as tree trunks, rocks, posts, etc., to attract the newly hatched queens.

However, the actual genetic mechanism of haplodiploid sex determination in bumblebees is more complex than simple chromosome number.

Because of this, cooperation among kindred females may be unusually advantageous, and has been hypothesized to contribute to the multiple origins of eusociality within bumblebees and other hymenopterans.

Larvae are fed a mixture of pollen and nectar combined with proteins secreted by adult bees.

The nectar is stored in a special internal pouch called the crop, while pollen collects on the hairs on the bumblebee body.

At the nest, the contents of the nectar crop is regurgitated, where it is mixed with enzymes and allowed to air dry.

[9] B. ternarius, as well as other members of the genus Bombus, live in eusocial colonies in which the individuals in the group act as a single multiorganismal superorganism.

Eusociality may have evolved in the bumblebee ancestor as a result of offspring remaining in the nest as adults to help rear their mother's young.

However, the queen's retaliation proves insufficient in some cases and the aggressive reproductive bumblebee workers kill her.

[23][34] This approach means inexperienced foragers waste less energy and more pollen is returned to the nest, maximizing the colonies' evolutionary success.

[14] One would predict that food patches nearest to the nest would be most visited, so would offer the least uncollected nectar and pollen.

[23] Long ago, foragers of a range of different bumblebee species were noticed to tend to be larger, on average, than bees that performed within-nest work.