Letters

Background for readers joining us here:

In BfDJ66 and 67, Pam Gregory discussed the need, when making top-bar hives for African races of Apis mellifera, to have accurately cut top-bars usually of 32 mm. In BIDJ69 Bernhard Clauss emphasised the need for accuracy with top-bars, but advocated 33 mm. In BfDJ70 André Romet described the method used successfully in Cameroon of cutting top-bars 22 mm and using a plastic sheet to cover. Here is Pam's response to André.

Dear Friends

I was interested to read André's letter about top-bars and enjoyed the beautiful photographs of well drawn out combs on neatly made top-bars that show just how obliging bees can be when they are given the right care. lam sure that BIDJ readers understand that there are many ways of doing the same thing in beekeeping. The overriding principle of both the top-bar techniques described (32 mm or 22 mm plus 10 mm spacing) is that the bees need the correct spacing if they are to build their comb in the desired manner. Getting the spacing right is the key to persuading the bees to build a single comb under a single top-bar, essential for successful top-bar beekeeping. Achieving this is an interesting problem for the beekeeper. Top-bars cut to 32 mm serve several functions. Firstly, the spacing Is automatically maintained so there is no chance of the top-bars being pushed too close together during the comb building phase resulting in combs being built across several top-bars. Secondly, the top-bars form a complete cover across the top of the hive. This means that when the hive is opened only a few top-bars at a time are removed, thus restricting the chance for the bees to come upwards out of the hive. Thirdly, they form an additional roof covering that acts as another line of defence against pests and water leakage. Simple measuring tools such as a nine volt battery or a coke bottle top can be used to help cut the top-bars to the right size. | have seen excellent top-bars made from bamboo and raffia palm materials. If they are a bit wobbly, propolis fills up any spaces. Gentle handling and careful smoking when moving the top-bars apart reduces any upset to the bees. However, tapping the top-bars hard to find out where the combs start is guaranteed to annoy the bees.

The method André suggests is a perfectly functional and acceptable alternative, although I have to confess to being perplexed as to why it should be simple to cut a 22 mm top-bar while being difficult to cut a 32 mm top-bar.

However, the accompanying picture gives the clue as to why this is not normally the recommended technique. The biggest problem lies in the spacers, which have to be an exact measure to keep the top-bars apart at the correct distance. This adds an extra difficulty in measuring, making and using the hive. | have experimented with al! sorts of spacing methods and invariably found them unsatisfactory. Plastic or very thin metal as shown in the picture is ideal but requires sophisticated fabrication and/or materials that are less likely to be available than carpenters. The spacers shown look very much like the castellated spacers many UK beekeepers use to space frames. Interestingly, top-bars at 22 mm are exactly the same size as UK manufactured frame tops.

Finally, although the bee space principle applies to both Apis mellifera and Apis cerana, there are significant differences between races and subspecies of both these bees. This means that centre to centre comb spacing can vary from 28 mm for some subspecies of Apis cerana to 35 or even 37 mm for Apis mellifera ligustica (the Italian bee). By and large African races of Apis mellifera honeybees are smaller than European races of Apis mellifera and so the bee space is smaller hence the use of 32 or 33 mm top-bars. This is also the reason why hive specifications may vary slightly from place to place. It is always best to adopt the local specification as long as it is based on sound science and accurate - measurement.

Pam Gregory