Bombus terricola

Kirby, 1837

Yellow-banded Bumble Bee, Yellow-banded Bumblebee

Bombus terricola, the yellow-banded , is a North American bumble bee native to southern Canada and the eastern and midwestern United States. The has experienced significant declines since the late 1990s, with range contractions particularly severe in its southern distribution. It is now classified as vulnerable on the IUCN Red List and listed on the Xerces Society Red List of endangered bees. The species exhibits complex behavioral traits including for cold-weather and adaptive responses to queenless nests.

Bombus terricola by (c) USGS Native Bee Inventory and Monitoring Laboratory, some rights reserved (CC BY). Used under a CC-BY license.

Bombus terricola by (c) Bill Keim, some rights reserved (CC BY). Used under a CC-BY license.

Pronunciation

How to pronounce Bombus terricola: /ˈbɒm.bʊs tɛˈrɪ.kə.lə/

These audio files are automatically generated. While they are not always 100% accurate, they are a good starting point.

Identification

Distinguished from the closely related rusty-patched (Bombus affinis) by the yellow-brown hair fringe on the fifth abdominal segment; B. affinis shows a rusty patch on the second abdominal segment. Differs from Bombus occidentalis in abdominal color pattern; B. terricola lacks the white tail tip characteristic of some western . Males can be distinguished by the additional yellowish-brown on abdominal segment 7. The is most reliably identified by the combination of yellowish-brown thoracic front and specific abdominal segment coloration pattern.

Images

Appearance

Queens measure approximately 18 mm in length. The front half of the is yellowish-brown, as are abdominal segments 2, 3, and 4, plus the sides of segment 6. The remaining thoracic and abdominal areas are black. A distinctive fringe of short yellow-brown hairs marks the fifth abdominal segment. are smaller, ranging 9–14 mm, with similar coloration to queens. Males are intermediate in size at 13–17 mm; males show yellowish-brown on abdominal segments 2, 3, and 7, with sides of segment 6 usually yellowish-brown.

Habitat

Occupies diverse including meadows, grasslands, wetlands, woodlands, farmlands, and urban areas. In Maine, associated with higher elevation sites. Found in alpine meadows to lowland areas. Agricultural sites with agricultural land use within 500m or greater than 10% land cover within 1000m are utilized, though these may expose bees to .

Distribution

Native to southern Canada and the eastern and midwestern United States. Historical range included 28 states in the eastern and upper midwest United States plus Washington D.C. and two Canadian provinces. Range has severely contracted since the late 1990s; extirpated from Illinois and disappeared from large portions of former range. Remnant persist in Vermont, New Hampshire, Maine, and the Great Smoky Mountains.

Diet

Nectar and pollen from diverse flowering plants. Documented foraging on milkweed (Asclepias syriaca), jewelweed (Impatiens biflora), fireweed (Chamaenerion angustifolium, formerly Epilobium angustifolium), and Apocynum androsaemifolium. Visits 12–21 flowers per minute during foraging bouts. Agricultural crops pollinated include alfalfa, potatoes, raspberries, and cranberries.

Life Cycle

Eusocial colony cycle with three phases: colony initiation ( produces first from ), switch point (queen transitions to haploid eggs producing males), and competition point (worker aggression toward queen and each other with reciprocal oophagy). Queens typically mate once during a single mating with multiple males, storing sperm in a spermatheca. Workers can lay male eggs in orphaned colonies with declining queen vigor.

Behavior

Exhibits : maintains thoracic temperature of 29–30°C for , shivering to generate heat in cold conditions. Lands on flowers to warm up when thoracic temperature drops below flight threshold. Foraging differs by resource type: nectar collectors arrive at lowest flower tier and move upward; pollen collectors arrive at middle inflorescence positions. Avoids revisiting depleted flowers, using either flower memory or landmark memory. Buzz pollinates by emitting 1–4 sharp one-second buzzing sounds while rotating clockwise or counterclockwise. Can adapt to queenless nests. Flight between flowers is relatively inefficient compared to sympatric Bombus ternarius, leading to differential use of flower patches based on spatial .

Ecological Role

Important of wildflowers and agricultural crops. Better pollinator than honey bees for certain plants due to buzz pollination capability and cold , enabling pollination in cooler conditions. Contributes to plant-pollinator network interactions; in Maine, showed 73% plant overlap with Bombus ternarius but foraged on fewer total plant species.

Human Relevance

Significant agricultural for crops including alfalfa, potatoes, raspberries, and cranberries. Subject to conservation concern due to declines; listed on Xerces Society Red List of endangered bees and classified as vulnerable on IUCN Red List. U.S. Fish and Wildlife Service reviewed for potential Act listing. Decline attributed to urban development, intensive agriculture, exposure (neonicotinoids and/or fipronil), and spillover from managed bees including Nosema bombi, Nosema spp., Crithidia spp., and Trypanosoma spp.

Similar Taxa

Bombus affinisClosely related phylogenetically and in signaling; so similar that B. affinis can invade and dominate B. terricola nests without detection. Distinguished by rusty patch on second abdominal segment versus yellow-brown fringe on fifth segment in B. terricola.
Bombus occidentalisFormerly speculated as of B. terricola but now recognized as distinct. Western with different abdominal coloration patterns.
Bombus ternariusSympatric in many areas; B. terricola is less efficient at flying between flowers and tends to use denser flower patches, while B. ternarius uses more widely spaced flowers. B. ternarius forages on more plant with broader distribution in Maine.