Sometimes the best advice/knowledge you can get in the beekeeping industry is advice from fellow beekeepers. What follows are questions about indoor wintering posed by commercial beekeepers who are considered storing bees indoors. Those questions were given to commercial beekeepers who have fully integrated indoor storage as part of the management of their operation. 
WHEN SHOULD I PUT BEES IN THE BUILDING?
The observant beekeeper knows the long-term temperature averages in the area where his bees will be stored. For example, in North Dakota, drones are being purged by October 5th, and some hives actually achieve brood-free conditions by October 10th.

Hives [double deep] should weigh 120-125 pounds on average by October 15 in Northern tier states. Ideally, daytime highs upon indoor placement are in the 40-degree range. The idea is to store bees as they approach, or enter a dormant state.

​For North Dakota, load the building after mid-October & finish by November 10.
HOW LONG SHOULD HIVES STAY INDOORS?
​Hives can be safely wintered indoors for months. Unlike outdoors, the hive is in a constant environment. Buildings are very dark. Ideally, buildings are very quiet. Temperatures are constant. Disturbance is limited. No flight occurs. Hives must be well-provisioned and healthy prior to storage. In many instances, hives are in storage for 60-80 days.
EXAMPLE SCHEDULE WHEN BEES ARE TO BE PLACED IN ALMOND POLLINATION:
Optimally, hives arrive in the orchard > 21 days prior to bloom. On average, almond blossoms begin to open February 15. Ideally, hives arrive prior to January 25. Upon arrival, hives should be promptly placed in pre-designated sets. Upon placement, hives can acclimate for 48 hours without drift issues, locate sources of water, and take cleansing flights. Hives should then be worked. Priority: a clean bottom board, a clean feeder, 2 pounds of pollen substitute and feed. This stimulates brood rearing. On February 14, the first brood hatch begins. These infant bees free old bees to forage.

​As the number of emerging bees increases, and as old bees die off; the hive is less stressed to meet the growing abundance of fresh almond pollen. Beehive frame counts need not contract through the end of February, when many measured strength inspections occur.
WHAT ARE CONDITIONS INSIDE THE BUILDING?
Ideally, temperature will range between 37-42 degrees F.

Humidity is controlled in a range not to exceed 50%. As bees consume feed, the by-products are heat created by muscle use, and humidity from respiration.

​Environmental controls are achieved by moving air. Some buildings move air without refrigeration. These buildings are vulnerable to the random warm day[s]. Most buildings use refrigeration to maintain constant temperature regardless of outdoor temperatures. The indoor temperature remains near constant.
WILL BEES SUFFOCATE?
A pillar of successful indoor storage is: Don’t suffocate the bees.

All refrigerated buildings re-circulate a portion of previously refrigerated air.

​For example, when outside temperatures are 0 F., the refrigeration easily meets the created heat ‘load’ from the beehives. However, fresh air minimum draws are a foundation of good storage practice. For example, never less than 5% fresh air is a minimum standard for virtually all refrigerated indoor storage buildings. The 5% is a threshold to prevent suffocation. Equally important is control of CO2 levels. If CO2 thresholds exceed certain levels, air handling devices can be pre-programed to introduce more fresh air. When outside temperatures are 0 F., refrigeration may be limited, or unnecessary, with fresh air providing the necessary cooling. It is important to consider where and how air is being distributed in the building and how the hives are stacked to make sure air flow is relatively equal around all the hives.
WHAT CONTROLS THE AMOUNT OF LIGHT IN A BUILDING?
Modern buildings are tight; i.e. virtually no light disturbs the bees.

When indoor work must be accomplished, several approaches work.

Some buildings use fluorescent tube lights, with red tubes covering the white.

Some buildings use red LED lights.

​Red lights are less disturbing to the bees, creating less flight. Loading crews can see their work. Employees wear red LED headband lights. Many of the buildings have systems set up around all the air ports to block light. Doors are well-sealed
WHAT ARE THE LOGISTICS OF LOADING AND SHIPPING A BUILDING?
​Entirely uniform hives, across outfits from 10 to 100,000 is not possible.

Prior to loading a building, the floor of the building floor may be gridded with painted stripes, or color-coded tape to direct stacked-hive placement in conformity with plenum-designed building airflows. The same tactic can be used to identify groups of hives identified prior to loading as: heavy and strong; light and strong, weak and heavy, weak and light, and so on. When done right, shipping crews can ship pre-designated hives to meet different customer requirements.

Safety is a priority: Many buildings have Overhead Doors (OHD) on each end of the building. The OHDs allow semis to pull in and pull out in a straight line, maximizing crew access to the ‘loads’ designated to a region or a customer in California. Additionally, once the semis are in place for loading, both OHDs are closed, eliminating outside wind/light interference.

​Often, buildings are outfitted with a sturdy overhead cable and safety harness for use when setting nets and load-securing devices. In cold country, a tarp is placed at the front of the load to eliminate undue chilling.
DO HIVE CONDITIONS CHANGE WHILE IN STORAGE?
A building is not a hospital. Queenless hives will still be queenless after indoor wintering. Many Varroa destructor will die indoor wintering – emerging data ​now documents CO2 levels maintained over a length of time will kill Varroa. Varroa in a brood-free colony have no place to reproduce. However, a hive with Varroa levels above well-documented thresholds will die either inside a building or shortly after. Poorly provisioned hives will starve. 
WHAT PREPARATIONS SHOULD HIVES GET BEFORE GOING IN?
​If beekeepers are used to shipping bees to California for the winter, they are often able to feed or do some hive repairs during the winter months. For indoor wintering, the hives need to be fed to proper weight. Mite levels reduced (ideally by September) and hive strength needs to be 8 frames or better. Feeding, mite treatments, combining hives are all things that can be done during the winter when bees are stored in California, all this needs to be done before “going in”. Hive bodies should be in good repair, and tight. Covers must be sound. Pallets must be cleaned of field debris including soil, manure and weeds. Broken pallets should be replaced. Broken pallets collapse. Collapsed pallets cause domino stack-collapse catastrophes. Eliminate hive beetles and red imported fire ants. For pre-inspected indoor buildings; these are mandatory standards.
WHAT TENDING WILL HIVES NEED UPON COMING OUT?
​Need to consider that the bees are highly prone to drift after coming off the truck following indoor storage. Need to take care in spreading hives out and arranging the pallets off the truck to reduce drift. Clean the bottom boards. Honey bees continually perish. Housekeepers may carry the accumulating dead to the entrance, and drop them. Housekeepers may witlessly carry the dead from the entrance, into the pitch-black abyss, unable to return and are soon death-chilled. Upon coming out: Open the hive, clean the feeder of any residual feed and accumulated dead bees. A clean hive is a healthier hive. Provide nutrition. Pollen substitute and feed are immediate needs.
HOW MUCH WEIGHT DO HIVES LOSE DURING STORAGE?
​Completely dormant hives in a 37-42 F. building will consume about 2 oz. of feed daily. Some hives more, some hives less. The arithmetic: if a hive is stored for 75 days in optimal conditions, @ 2 oz./day = 150 oz. or 9.5 lbs. of feed. Many beekeepers follow a 4 oz./day formula = 75 days @ 4 oz. = 19 lbs. The pillar is: Don’t starve hives. Amazingly, a percentage of hives begin rearing small patches of brood around January 1; hence the ample feed recommendations.

If a hive weighs 120 lbs on November 1st, by January 15, it will weigh around 102 lbs upon shipment. If a semi can haul a 48,000 lb load; a beekeeper can safely ship 456 hives on the semi. If a hive weighs 130# on November 1st, by January 15th, it will weigh around 112 lbs. The 48,000 lb load is about 420 hives. 10,000/456 = 22 semis.

10,000/420 = 24 semis. An 1800 mile one-way trip @ $3.35/mi. = $6,030.

​Two loads @ $6K = $12,000; or most of the cost of a tanker load of syrup.
ARE DEAD BEES REMOVED FROM THE FLOOR FROM TIME TO TIME, OR IS IT BETTER TO NOT DISTURB THE STORAGE?
Some storage buildings are cleaned from time to time; others not at all.

The pathogens that may or may not be encased in the dead bee husk are not known.

Bees perish continuously. The floor becomes covered.

Various methods are practiced. Some beekeepers use industrial vacuums to clean the floor. Vacuums must be emptied upon each use, or when full: bees will decay in an enclosed vacuum.
Some beekeepers sweep between columns and rows. The swept bees can be stored in a closed bottom tote for later removal. Again, bees decay, and ‘leak’ from the bottom of leaky totes, drums, boxes, dumpsters. 

​15,000 hives will shed about 5 - 275 gallon totes from November 15 to January 15. If bees are not cleaned from the floor, bees must be cleaned upon shipment, lest the floor becomes a slippery mess. In these conditions, the humans wear respirators. What about the bees?
  •  If sweeping occurs regularly – every 48 hours, the building will stay clean.
  • Irregular sweeping becomes an overwhelming ‘push’ between rows and columns.
  • Stacks are often 6-8 pallets high; hence the numbers of dead accumulate.
  • The gridding of the floor works great when sweeping between stacks when the stacks are 25” apart. 24” brooms glide between stacks. 23” between stacks does not accommodate 24” brooms.
  • Centers of the building are open. This allows use of 48” brooms.
  • A good scoop shovel and several totes throughout the building reduces work.
  • It is easier to keep a building clean than to get a building clean.
  • Dead bees accumulate beneath pallets.
  • Calculate one mouse per every four pallets. If 4,000 pallets load in the building, so are 1,000 mice. Spam bait 40 mouse traps throughout the building. Inspect, empty, and reset traps regularly. 40 traps will yield 25 mice every 48 hours. By mid-January, fewer mice remain.
  • Never, ever leave a vehicle in the building (mice). Some buildings have floor drains. Some buildings have no floor drains. Some building floors are perforated for airflow. Each building design has virtues. Before investing in an indoor wintering facility; and certainly, before renting space in an indoor building: • Know the operator.
  • Define the terms of storage, access, and egress timing.
  • Know the other outfits with whom storage space will be shared.
  • A building is not a hospital.
  • Feed is not expensive until denied. It is a lot more expensive to lose bees to starvation.
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