A Middle Entrance for Beehives II
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We expect to demonstrate improvements in honey bee colony health and strength through using a middle entrance.
By relocating the hive entrance from the bottom of the hive to above the brood nest, we expect to reduce the population of Varroa mites in the hive. Mites do fall off bees, but in a typical hive, they land on the bottom board, and may catch a ride back into the brood nest on another bee. By putting an entrance above the brood nest there will be fewer free rides.
We plan to carefully monitor 20 new colonies for one year, monitoring Varroa population and hive weight, to assess the comparative efficacy of a middle entrance as a control alternative.
We are part-time beekeepers providing pollination to small farms in the Vineland N.J. area. Blueberries and garden market crops predominate, but there are also strawberries, apples, peaches and corn nearby. Some request that no harsh chemicals be used on the bees or hives to keep in line with their natural and organic ideas. We respect this, and strive to find ways to stay ahead of the mites.
In setting up our experiment we developed our skills in queen rearing to provide sets of queens with similar genetic backgrounds. This year we plan to sell queens and starter hives (nucs) to other beekeepers interested in obtaining bees which have survived in our area without chemical treatments.
We started 20 new colonies in early summer for this experiment. They were divided into 5 groups of 4 colonies. In each group there was one hive of each of the following configurations:
Solid bottom, bottom entrance – the standard hive
Screen bottom, bottom entrance – typical mite control
Solid bottom, middle entrance
Screen bottom, middle entrance
We began our project by obtaining the 20 special hive bottoms for counting mites from a beekeeping supplier, Mann Lake. They have a large screened opening in the bottom, and a tray that can be inserted below the screen on which the fallen mites will land. To assist in counting mites we made white pages with 1 inch squares marked on them for each tray. See Photo 1. We used self-stick clear shelf liner to laminate the paper to the tray. Also we made up pages with the same number of squares to facilitate recording the mites. With 20 hives being monitored every 2 weeks for a year, we made 540 photocopies, and put them in 3-ring binders, one binder for each group.
When the tray is removed, the bottom of the hive is open and any mites that fall will land on the ground. To simulate a solid bottom hive pieces of ¼” plywood were cut to slip in on top of the screen. This is actually an unpleasant operation when the bees are active, as the board is slipped in their guarded entrance, but even more unpleasant is removing the plywood false bottom when it is covered with bees.
Photo 1: Bottom Board for mite detection
This shows a screened bottom board, painted yellow, the mite collection tray with grid lines to the right, and a plywood false bottom board on the left. The front of the hive is at the left. The bottom is supported on the hive stand.
A carrying rack was also built, which allowed for transportation of the trays from various pollination yards.
To weigh the hives a special stand was built for each hive. It is shaped like an H made of 2x4s, laying crossways under the hive, so the long ends extend past both sides of the hive. Three pieces of pressure treated 1x6 deck boards were attached across the H to keep it off the ground, and provide support for the scale tower.
We used a hanging spring scale attached to a 2x4 tower with a rope and pulleys. The pulleys allow the operator to exert half the force, and have more control, than a single rope. A chain from the bottom of the scale hooks under the side of the hive, and is long enough that the operator can read the scale at eye level. The base of the scale is made to fit inside the H of the hive stand, resting on the pressure treated boards. The weight from each side of the hive is added to obtain the total hive weight. With this setup hives up to 300 lbs. can be weighed.
The weight of the hive equipment is subtracted from the total weight, so that adding another hive box doesn’t show up as a sudden weight gain. We will refer to ‘live weight’ as the total weight minus the equipment weight. Equipment weight includes the weight of the undrawn frames and foundation. Rite cell foundation was used, and most equipment was purchased from Harvey’s Honey, Monroeville, NJ. We took care to weigh the hives at dusk, so that we would not miss the weight of the foraging bees – although sometimes a few bees don’t get home for the night.
Photo 2: Scale Tower sitting in Stand
The construction of the hive stand can be clearly seen. The base of the scale tower provides stability and consistent positioning. The hook on the end of the chain is in an eye, to reduce swinging during positioning, which can arouse the bees by banging on the hive.
Photo 3: Dave Weighing a Hive
The help of another beekeeper with a decent woodshop was obtained in crafting the 10 middle entrances. The entrances consist of a ¾” rim the size of the beehive box, but extending out the front about 3 inches. A landing board is attached across the bottom of the front extensions. Through the middle area 3/8” slats cross the hive, with 3/8” spaces between them, filling the space so the bees don’t build unwanted comb. The slats are kept back from the front of the hive so there is plenty of space for the bees to enter and leave the hive.
Photo 4: Middle Entrance
Photo 5: Middle Entrance in place Photo 6: Complete Hive
In anticipation of starting the hives for the experiment we raised queens and established an isolated mating yard to provide sets of sister queens mated to drones from one colony, thus reducing the variability of the queens in the experiment. We also purchased one set of 4 queens from another supplier (Purvis Brothers Apiaries, Georgia) which claims to have Varroa resistant bees.
The new colonies were started in July. For each group a large hive was split into 4 hives, trying to have a balance of bees and brood, and a queen was introduced to each. Frames from the large colony which did not have brood were not used. The rest of the box was filled with foundation frames. The middle entrances were placed on top of the first hive box.
The mite loads on the large hives was not high, meaning that there were some mites which could be found, but bee health did not seem to be affected.
We had the opportunity on July 19, to host a meeting of the local South Jersey branch of the New Jersey Beekeepers Association, and demonstrate setting up one of the groups of hives.
We began feeding the hives immediately, using 1 gallon quail waterers placed in boxes on top of each hive. We fed them HFCS from a local fountain soda distributor. We continued feeding until early October. Two groups were placed at a small farm with mixed crops and a 2 acre garden area. Two groups were placed near a cornfield, where pollen was readily available. The last group stayed at the home apiary, which is mostly woodlands with small family clearings, some having gardens. The new hives were not large enough to be considered for pollination work.
The hives were all brought back to the home apiary for the winter months, through to February 9. At that time the hives were given pollen patties to stimulate spring growth.
We expect that the spring growth period will last through until early April, when spring pollination will begin. June through early July is usually the honey production period. We will continue to monitor the hives through those stages.
Feeding stage - July to October
Not all hives or groups gained weight at the same rate. Typically they gained 6 lbs for every gallon of syrup. One hive gained 90 lbs, but 60 was average. One hive failed to gain weight, and we suspect the queen was at fault. The group at the home apiary gained weight much slower than the others, 40 lbs typical, which could be due to lack of good pollen sources, as there were other stronger hives competing for resources, or due to the hives being positioned in a shadier location. No apparent differences were noted when hive configurations were compared.
The mite counts were not as we expected. The mite population should grow as the hive grows, and there was that trend to it. Average mite fall at the start was about 3.5, and at the end was about 5. More apparent than the trend were the variations. A hive could have no mites fall one time, and have the most of any in the group on the next count. This is very important for beekeepers which would try to rely on natural mite fall counts to determine treatment strategies.
Winter Stage - October to February
We had some hive losses during the winter.
The hive which did not gain weight perished early, in November. We could predict that, but we did not interfere. The little honey which they had collected was robbed out by the others on warm days. It had a screen bottom, and middle entrance.
Three of the hives which were raised in the home yard perished one cold night in early January. Although there were still over 20 lbs of stores in each, the number of bees was too small for the cluster to stay warm. The other hives began raiding the generous provisions on the warmer days. The one that survived had screen bottom and middle entrance configuration. It had gained more weight than the others, reaching 50 lbs.
One hive died due to a loss of queen, probably from transporting the hive in the fall. It had several emergency queen cells built, and apparently hatched, but queens can’t fly to breed in the cold weather. Without a mated queen the colony dwindled in number until it died in late January. It was a screen bottom with bottom entrance hive.
In early February a hive with a closed bottom and middle entrance perished. It had clustered in a portion of the hive which did not have honey near it. It still had about 40 lbs of honey available.
This period lasted 18 weeks, and typical weight loss was 20 lbs. Some larger hives lost 30 lbs. The average live weight of the remaining 14 hives is about 45 lbs. Of the hives that perished, 3 had screen bottom, 3 had closed bottom, 3 had middle entrances, 3 did not. No apparent difference in hive weight or weight loss is noted between different hive configurations.
The average mite counts continued to climb until early November, but hives peaked at different weeks. We focused on the peak value for each hive (the average of the highest two counts for the hive), divided by the hive’s maximum live weight, to give a maximum mite load. Values ranged from 1 mite per 20 lbs to 1 per 4 lbs, averaging 1 per 7 lbs.
Group averages ranged from 1 per 5 lbs to 1 per 15 lbs. This variation may reflect on the beginning mite load in each group.
When assessing hive configuration differences the screen bottom hives had 1 mite per 9 lbs, compared to 1 mite per 6 lbs. for solid bottoms. Middle entrances had 1 mite per 7 lbs, and bottom entrances 1 per 8 lbs. The variation is too great to conclude a significant difference. With the fluctuations on mite counts more data needs to be collected.
The mite fall rate plummeted after these peak rates, and average was around 1 from the end of November through the middle of January. We suspect that this coincides with the cessation of the bee brood rearing. Some hives began to drop a few more mites in late January, and are increasing in February. In this area it is not uncommon for the hives to begin brood rearing in late January.
We do not have any concerns of unusual farming conditions affecting our research so far.
While we regret the loss of colonies, we consider that to be part of the project. However, we plan to consolidate the groups into 4, by including the single hive left from one group in another group which is missing that configuration. This would make 2 groups of 4 and two groups of 3, barring any further losses. This has reduced the effort required to check all the hives, as there are only 14 instead of 20.
Thus far we have established techniques and equipment for monitoring hive performance, but we have not tested the hives against the full challenge of dealing with Varroa mites. By this we mean that starting a new colony in July is one method of staying ahead of Varroa mites, but the true test is to follow the hives through a whole spring, summer and fall session. We have applied for a SARE grant extension through the second year, and expect to find more patterns in mite fall. We also expect that the advantages of various hive configurations will become apparent when the bees are actually foraging.
Thanks for your interest, and thanks to Tim Schuler, NJ State Apiarist, who continues his involvement as advisor.