Wax foundation, being produced as horizontal comb, prevents vertical comb being present within the hive. Natural comb in feral colonies very often produces brood nests comprising of vertical comb. Feral colonies appear to survive in areas of varroa infestation; colonies containing vertical comb.

The question therefore arises as to whether this type of comb is in someway detrimental to varroa reproduction.

It is general knowledge that the mite when entering the cell prior to capping, hides behind the larva which is curled up at the far end of the cell. It is also accepted that if a visiting nurse bee observes the mite in the cell prior to hiding behind the larva, the bee will remove the varroa. This is a period of danger for the varroa.

Although the varroa is deemed to have some aquatic ability regarding bee milk, I feel that the attempt to pass between the larva and the cell wall would be made where the conditions were the most favourable, namely where it is dry and the pressure is least. The pressure between the larva and the cell wall is greatest at the bottom of the cell due to gravity and the weight of the larva. The pressure is least at the top.

With horizontal comb, with the apex at the top, a small triangular space occurs above the larva and the mite therefore may gain easy access. The conditions are also dry. Where vertical comb is present and the flat portion of the hexagon is uppermost this ease of access is no longer available. Diagram refers.



The longer the time that the varroa takes to hide itself, the greater the likelihood becomes of a nurse bee inspecting the cell and removing the mite. Experiments are currently being undertaken to test this theory as to whether cell infestation is less when vertical comb is present.

It is interesting to note that the pressure between the cell wall and the larva may also be increased, and no doubt cause a similar effect, by decreasing the size of the cell, or by introducing a queen mated, or bred from, a slightly larger strain.

In the insect world there are numerous instances where the parasite is aware of its host's location, which with only our senses, would appear impossible. J.H. Fabre has been consulted and is of the same opinion.

A parasite wishing to lay its egg adjacent to its host's larva achieves its purpose because it can detect the location, age and health of the larva through the equivalent of a brick wall. The senses the parasite uses are beyond our comprehension or even acknowledgement. Although varroa are not insects, there is no reason why they should not also have this parasitic capability.

Varroa do not just turn up prior to capping by pure chance, and with this ability they would be aware of the position, age and health of every larva in the hive, and could map their course accordingly. If this were the case, regular manipulation of brood frames, where the frames are reshuffled rather than replaced in their former position, would confuse both bees and varroa which would be detrimental to the varroa regarding nest site location.

The confusion to the bee is difficult to quantify, but 'chewing out' may be a sign that the bees are not happy with the new brood nest shape and are rearranging matters more to their liking.

Whether the penetration of this special awareness is effected by the presence of metal, such as a sheet of queen excluder, is open to further speculation. In fact, queen excluders may already play an important roll in varroa reproduction in two ways.

(1) Varroa bred in drone cells that remain on the drone after emergence from the cell will be retained in the brood nest area due to the queen excluder.

(2) The queen excluder would act as a safety net for groomed varroa formally attached to worker bees operating in the upper part of the hive.

Not only may varroa have this special awareness of the bee, the bee may also have a special awareness of the varroa.

It is dark within the cell, so the bee's recognition of the varroa will not be ocular, but by this special awareness that can identify other life forms through intervening material. However, this awareness apparently will not penetrate through the life form of the larva, and in consequence the life form of the varroa remains undetected.

It is also equally possible that the varroa knows that it will be seen by the bee unless it hides its life form behind the life form of the larva.

The varroa is aware of the bee's awareness, but are we aware of the varroa's awareness; I think not.

- Ian