Fernald cuckoo bumble, Bombus flavidus/fernaldae

Field ID tips

The Fernald cuckoo bumble has a continuous yellow band on T4 (no black interruption).

  • T1 = black
  • T2 = black
  • T3 = black
  • T4 = yellow ( insularis, would show a black area in the center)
  • T5 = black (drones may show some orange or pale hairs)

Similar Species

We have three species of cuckoo bumbles in Washington state.

The Fernald cuckoo bumble bee can be distinguished from the Indiscriminate cuckoo bumble bee because the Indiscriminate bumble has a yellow face and a black notch on T4 while the Fernald cuckoo has a black face and a solid yellow T4

The Fernald cuckoo bumble bee, in the west, is a dark bumble. T3 is black. If T1 is yellow or cloudy, then this is not a reliable field mark.

In the Suckley cuckoo bumble bee, T3 is yellow with a black notch. In the case of B. suckleyi, T1 is always black on a queen. So, if T1 and T3 are black, it is most likely a Fernald cuckoo. If T1 is black and T3 shows some yellow, it may well be a Suckley cuckoo bumble bee. If T1 is cloudy, not black or yellow, it suggests Fernald not Suckley.

The key distinguishing feature for separating B. flavidus from B. suckleyi, the Suckley bumble bee, according to the key in Bumble Bees of the Western United States, by Koch, et al, 2012, is the color of the hairs on the back of the head (Occiput). If the hairs on the back of the head are predominantly black it is B. suckleyi. Bombus fernaldae has mainly yellows hairs on the back of the head. This is important to remember, as far as capturing the key elements needed for photographic identification. Make that shot!

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