Bombus fervidus, the golden northern bumble bee or yellow bumblebee, is a species of bumblebee native to North America. It has a yellow-colored abdomen and thorax. Its range includes the North American continent, excluding much of the southern United States, Alaska, and the northern parts of Canada. It is common in cities and farmland, with populations concentrated in the Northeastern part of the United States. It is similar in color and range to its sibling species, Bombus californicus, though sometimes also confused with the American bumblebee (Bombus pensylvanicus) or black and gold bumblebee (Bombus auricomus). It has complex behavioral traits, which includes a coordinated nest defense to ward off predators. B. fervidus is an important pollinator, so recent population decline is a particular concern.
Taxonomy and phylogeny
Danish zoologist Johan Christian Fabricius first identified Bombus fervidus, also known as the yellow bumblebee or golden northern bumblebee, in 1798. B. fervidus is a member of the order Hymenoptera, which comprises wasps, ants, bees, and sawflies. Bombus is the Latin word for "buzzing". It is also in the Apidae, which is a diverse family of bees including honeybees, orchid bees, bumble bees, stingless bees, cuckoo bees, and carpenter bees. It is very closely related to Bombus californicus, and in many areas of geographic overlap, at least a small percentage of individuals of the two species cannot be recognized except by genetic analysis, as each species can sometimes display the color pattern typical of the other.
Description and identification
Bombus fervidus is on average 13–16 mm long However, there are slight differences in morphology between queens, workers, and drones (see table below). The first four abdominal tergites are yellow. The occiput and face are black, and have yellow pleurae extending to or nearly to the bases of the legs. A black band is present between the base of wings. The wings are dark to dark grey colored. The hairs are thick. B. fervidus is long-tongued and therefore specializes on flowers with long corollas. B. fervidus use long tongues to extract nectar and pollen from longer flowers. Males have slightly more yellow on their abdomen, and are difficult to distinguish from B. pensylvanicus and B. californicus. Males have a wingspan of 22 mm while female workers have a wingspan of 40 mm.
Distribution and habitat
B. fervidus is native to Canada, Mexico and the continental United States, and individuals in its genetic lineage are more broadly distributed than previously suspected.
The species prefers temperate savanna, grassland and tall grass biomes, and readily coexists with suburban or agricultural developments. It is common in grazing farmlands.
Nest
The nest of B. fervidus is a loose mass of soft, lightly entangled grass mixed with goose or other feces that are most likely carried in and arranged by the bees themselves. B. fervidus generally nest in grassy, open areas, which includes forests and along roadsides. Nests can be located both above and below ground, but the latter is more common. Nests are typically within 50 meters of a food source sufficient to feed the entire growing colony.
Colony cycle
Bombus fervidus queens lay eggs individually in cells within the nest that she builds herself. She first lays 8-10 eggs, one in each cell. When these eggs hatch, the larvae emerge and feed on honey for growth. The queen makes the honey for the larvae until they are ready to pupate, which is when the larva create cocoons for themselves where they stay to metamorphose into adults. Metamorphosis typically takes 16 to 25 days. Once the adults bees emerge from the cocoon, they are adult workers. This first generation of the brood that becomes workers are responsible for feeding the next generation of developing larvae and the queen. This ensures that the queen can focus on laying more eggs. Thus, each generation of B. fervidus is larger than the one before it.
Nest population
A typical nest contains four eggs, fifteen larvae, forty-two pupae and seventeen adults. Ten of the adults are worker adults, containing small undeveloped ovaries with no eggs, while the remaining adults are males with mature sperm. The pupae are 37 males, 5 future workers and only one queen. The larvae fall into three groups – large (nearly full grown), small or indeterminate. Workers typically live on average for 34.1 days.