What is the optimal window of time in the UK to observe Bombus vestalis queens?

Answer

Early spring from March to May

This time frame corresponds with the period when newly mated queens emerge from hibernation to seek out vulnerable, newly founded host nests. Active searching behavior by the parasitic queens is most prominent during these months, making it the ideal time for enthusiasts to spot them as they hover near potential nest sites.

What is the optimal window of time in the UK to observe Bombus vestalis queens?
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