Non-surviving colonies that die overwinter (they're discovered in spring), or colonies suddenly without a sufficient population of adult bees in fall, followed by death of the entire colony.
A colony may die for a variety of reasons. It is best management to do a necropsy on a dead hive to determine what might have been the reason(s) for non-survival.
The major reason for sudden loss of a colony or heavy colony loss overwinter is a virus epidemic related to varroa mite infestations. Colonies may collapse in the fall after showing parasitic mite syndrome (PMS), once labelled (beginning in 2006) as colony collapse disorder (CCD) or previously as many other names such as fall collapse, spring dwindle, May disease, etc.
Colonies may also die due to starvation (running out of food stores) overwinter or sometimes during spring buildup. Too few bees (due to disease, pesticide loss during the year, or to beekeeper management, such as splits or starting new colonies) may also lead to colony loss when temperature fluctuations occur, especially during the winter or early spring. A queen replacementqueen replacement:
removal of an old queen and installation of a new queen in a bee colony
that is not timely or successful can result in death of a colony. Colonies that topple or have covers blown off overwinter, or for which equipment is exposed or scattered by vandals or pests such as bears, might also die.
Colonies with dead, decaying brood and or dead adult bees have a sour, unhealthy smell. Fly maggot or beetle grub scavenger populations may expand rapidly and add to the unhealthy smell of decaying brood or bees.
Other reasons beekeepers ascribe to colony losses include pests such as wax moths, small hive beetles, yellowjackets, mice, shrews or moles, etc., which are signs of colonies that are too small or that have too much space for the bees to defend. None of these pests kill healthy colonies, but they readily scavenge as colonies die or weaken. Colonies with these other invaders have their own often distinctive smells. Colonies with wax moth or mice nests for example have a distinctive smell sometimes mingled with the smell of dead or decaying brood and adults.
absconding; PMS; CCD
Heck A. 2021. Can you reuse frames from a deadout bee hive with mouse infestation? #743047. Ask Extension. Accessed 2023. https://ask2.extension.org/kb/faq.php?id=743047
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Caron DM. 2021. Necropsy of a hive. Honey Bee Medicine, Chapter 27. Wiley Blackwell, Hoboken, NJ, US. 400 pp. https://onlinelibrary.wiley.com/doi/epdf/10.1002/9781119583417.ch27
Milbrath M. 2020. Dealing with Deadouts. American Bee Journal 160(3): 273-275. https://bluetoad.com/publication/?i=649618&p=41&view=issueViewer and https://bluetoad.com/publication/?m=5417&i=649618&view=articleBrowser&article_id=3599915&ver=html5
Conrad R. 2019. Evaluating Dead Colonies. Bee Culture. Accessed 2023. https://www.beeculture.com/evaluating-dead-colonies/
