Greater wax moth in Cheshire

The photo shows damage to a brood frame caused by Greater wax moth. The frame was one of a set, complete with wax comb, which was being stored in a spare Dadant brood box in mid-Cheshire.

This is the first time I have seen such damage to equipment in Cheshire, the Greater wax moth being common in the south of the UK but rarely seen this far north.

Could this be a result of global warming, or perhaps it has something to do with the use of wax moth larvae by fishermen...

Beware! Wax Moths

There is a natural tide in the life cycle of Wax Moths.

In tropical and subtropical zones wax moths can survive breeding cycles without interruption, but in temperate regions low temperatures alter their biology. So-called 'global warming' is changing the rules and beekeepers may unwittingly be encouraging an increase in the UK wax moth population!

Last season's chrysalises were able to hibernate in areas close to the brood nest, subject to not being exposed to the housekeeping attentions of the bees. When temperatures rise to become more favourable for breeding purposes, the cycle is initiated by the first female leaving the cocoon in which she has over-wintered in her final metamorphic stage. Once sufficiently mature she will leave the hive to seek a male for mating purposes and then attempt to re-enter the hive in order to complete her destiny by laying eggs to start a new generation of her species.

Even though the wax moths, both Greater and Lesser, are classic and ubiquitous hive inhabitants, only a minority of hives appear to suffer from massive attacks. During their evolution, bees have acquired the ability to defend their hives against wax moth attacks. They must be able to eliminate wax moth larvae because healthy and well populated bee colonies rarely loose combs to the moths, even though many larvae hide in places inaccessible to the bees.

In summer, bees constantly patrol the combs farthest from the brood nest and eliminate all moth larvae they encounter. It is fundamental that these 'moth hunters' prevent larvae congregations developing before the formation of the dense mass of threads that is impenetrable to the bees, and Which may subsequently lead to the total destruction of the combs.

But comb inspection by bees tends to drop in hives headed by deficient or weak queens at the end of the early flow. In such circumstances, there will inevitably be dark combs remaining from cycles of brood rearing in the weakened colony which constitute the ideal substrate for moth development.

There is a clear difference between vigorous and weak hives. Strong colonies mount a permanent entrance guard during the summer, its main duties being to repel possible insect intruders. Weak colonies guard their entrances less well.

A female can lay several hundred eggs!

The entry of a female moth into a weak colony to lay eggs may initiate the process of comb destruction and precipitate the desertion of the bees and untimely colony death, A female can lay several hundred eggs! The resulting larvae, if not removed by the bees, begin to degrade the combs by excavating tunnels or galleries, which are progressively converted into a dense jungle of threads that protect them from the bees. In little more than a month the combs of a complete colony may be consumed.

If there is a shortage of food in one hive, the larvae of the Greater wax moth are able to emigrate and invade other colonies. Larvae have been known to travel up to 50 metres to locate a new hive and fresh supply of food. Larvae opting to remain in the original hive on a reduced diet may complete their development and weave cocoons inside that hive, but the development time tends to be longer and the size of the adult moth is reduced.

In most cases, sooner or later, both the Greater and Lesser wax moths work in the degradation of the same colony. The size and voracity of the Greater wax moth larvae leave the Lesser wax moth larvae very much in second place. The Greater consumes the combs and the Lesser is relegated to survival on the remaining residues. The Lesser has adapted well to this austere diet and can be found where the Greater is unable to grow. The Greater plays its part in the primary degradation of combs and when these have been reduced to a pile of debris formed of tiny wax fragments, larval excrement, cocoon remains and threads, the larvae of the Lesser take advantage of the remaining residues by reducing its volume, finally leaving a black, aromatic, granulate dust as the end product of their joint action.

At the end of the summer the larval development starts to slow and progressively stops, almost completely. The last chrysalises hibernate and pass the winter in their cocoons, bringing to an end the annual cycle, only to await the dawning of a new year in the coming spring.

Keep wax moths at bay by maintaining strong, healthy colonies at all times, and be ever watchful for signs of wax moth eggs and larvae in your hives.

Bob Ogden (from Devon BKA's Beekeeping courtesy of BEES)

CHESHIRE BEEKEEPERS' ASSOCIATION

Apes curamus et nos curant (We look after bees and they look after us)

Founded 1899

Registered Charity No. 227494

Greater wax moth in Cheshire

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