Pests
Varroa Mite
Varroa destructor is an external parasitic mite that attacks the honey bees Apis cerana and Apis mellifera. The disease caused by the mites is called varroatosis.
Varroa destructor can only reproduce in a honey bee colony. It attaches to the body of the bee and weakens the bee by sucking hemolymph. In this process, RNA viruses such as the deformed wing virus (DWV) spread to bees. More here
A significant mite infestation will lead to the death of a honey bee colony, usually in the late autumn through early spring. The Varroa mite is the parasite with the most pronounced economic impact on the beekeeping industry.
What are its effects?
Varroa mites spread naturally between bee colonies by travelling on the bees. Modern beekeeping practices of moving hives and equipment between apiary sites have the potential to spread mites quickly over long distances.
One or sometimes more female mites enter a brood cell in the bee hive laying about five or six eggs each. Newly hatched (nymph) mites feed on the growing bee larva.Once mites reach maturity they mate, the males die; the females attach themselves to adult bees and feed by sucking their blood. A heavily infested colony may have mites on a third or more of adult bees or brood.
Attack by varroa mite weakens bees, shortens their lives, or causes death from virus infections that would otherwise cause little harm. In severely attacked colonies bees may have stunted wings, missing legs or other deformities. Unless urgent action is taken, the vitality of bees in the colony declines until all are dead.
Varroa mites can remain undetected for up to two years, by which time it is too late to prevent spread to other hives.
Sources: Wikipedia - BBC - Australian Government - Dummies.com
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Honey Bee Colonies and Wasps
Wasps can be a major problem for honey bee colonies in late summer and autumn. It must be remembered that use of poisons as controls may also kill bees and can be harmful for the beekeeper!
How many wasp species are there?
There are many species of wasp but most of these are solitary in habit and usually aren’t a threat to honey bees. In the UK there are six species that are social and create problems for bees and beekeepers. They are the common wasp Vespula vulgaris, the European hornet Vespa crabro, the red wasp Vespula rufa, the tree wasp Vespula sylvestris, the German wasp Vespula germanica and the Norwegian wasp Vespula norvegica. These are all eusocial, having a nest headed by a queen with workers (undeveloped females) who feed and care for their siblings, including drones (males) and virgin queens in late summer. There is also Vespula austriaca, which is a cuckoo species having male and female sexes only.
Yes, it may look rather cute but given the opportunity, Mice can create a lot of damage inside a bee hive...
Major pests in beekeeping
If care isn't taken, mice can be a major problem to the beekeeper. They will readily enter an occupied hive in winter where they will make a nest. They will destroy some of the combs and may cause so much disruption to the colony that it dies. Mice will also make a nest in stored equipment if not made mouse proof.
When bees are active they will deter mice themselves, but when they start to cluster on cold days in the autumn mice will seek entry. Mice are unable to get through a narrow gap of less than 8-9mm, so some physical form of denying them entry works. If you have a deep floor you will need to restrict the entrance in some way. This could be a flat metal mouse guard with holes in as sold by appliance dealers or an entrance block with a shallow entrance. I use shallow floors that prevent entry of mice.
When making entrance blocks or shallow floors a pencil can be used to size the gap, as I have never found a mouse will enter a gap so small. I don't like making mouse guards from queen excluder because a large amount of pollen is scraped off the legs of the bees.
Equipment that is stored needs to be protected, either by putting it in a mouse proof container, or if it is boxes of combs stack the boxes up with no gaps and put a queen excluder top and bottom.
Although equipment may not always cost much it is valuable when you need it and can't use it. The careful beekeeper will make sure that mice aren't a problem.
An extremely destructive Pest!
Wax Moth
Introduction
There are currently two known species of wax moth that occupy and damage honey bee colonies. Each one has four stages of development: egg; larva; pupa; and adult. The greater wax moth, Galleria mellonella is the more destructive and common pest whilst the lesser wax moth, Achroia grisella is both less prevalent and less destructive. Wax moth infestations are caused by unhygienic management practices; leaving scraps of burr comb lying around the apiary and empty and exposed supers or brood boxes with drawn comb in will attract moths. When the equipment is left over a long period of time, this gives ample opportunity for infestations of wax moth to get out of control. Drawn comb can become damaged and eaten away, making in unworkable for colonies of honey bees.
Although considered a minor pest, wax moths can cause damage to beekeeping equipment and to stored combs. They are a particular problem for colonies that are weak or diseased. Beekeepers are encouraged to keep strong and prolific colonies so that colonies are better able to defend against infestations.
Biology
Females oviposit eggs into crevasses and gaps within the hive where they remain out of reach of nursing bees. Once the larvae hatch, they immediately search for comb in which to feed. The thoracic legs are immediately visable and well developed and as the larva feeds and grows they develop, the abdominal legs become more prominent after around 3 days old. Speed of growth is directly dependent on temperature and food supply. Under ideal conditions the larval weight can double daily during the first 10 days.
A greater wax moth larva moults 7 times throughout its development. Most of the growth and size increase happens during the final 2 instars. Larval development lasts 6-7 weeks at 29° - 32° C and high humidity. As the greater wax moth larva matures, it will reach a length of around 20 mm and its body will turn grey in colour with a brown prothoracic shield having a broad band across it.
Mature greater wax moth larvae bore into wood and often make boat-shaped indentations in the hive body or frames. After finding a place in the hive to pupate, the larva begins spinning a silk thread cocoon, which they attach to the excavated indentations. The development stage of greater wax moths varies from 6 to 55 days, depending on factors such as temperature.
Adult moths reach a length of 15 mm long with a 31 mm average wingspan. The wings are grey in colour but the hind third of the wing, normally hidden, is bronze coloured.
Damage to colonies
The larvae of both species cause damage to comb by feeding on the wax, though they cannot survive on wax alone; larvae fed on pure bees wax have been shown to stop developing. They rely on other impurities within the wax - particularly cocoons in old brood combs. One obvious sign of a wax moth infestation is a white silk trail left by burrowing larvae moving below the cappings of honey bee brood. In extreme cases the whole of the comb will be destroyed, leaving a matted mass of silk, frass and other debris.
Mature greater wax moth larvae bore into woodwork and often make boat-shaped indentations in brood boxes, supers, crownboards and frames. After finding a place to pupate, the larva begins spinning silk threads to make the cocoon, which can be seen attached to the excavated indentations. On close inspection, one will find large amounts of cocoons congregated in areas around the periphery of the bee nest.
Control
Good strong colonies will not usually tolerate infestation by wax moth and it is not usually a problem in the field in healthy colonies. However, it is a problem in either weak colonies or hives where colonies have died or in stored combs. In the field hives should be kept as strong and healthy as possible, combs should not be left lying around the apiary and dead colonies should be removed as this will attract wax moths (basic apiary hygene!). Lightly infested boxes may be placed on strong colonies to clean out, but heavily infested combs cannot be effectively treated and should be burned. In the apiary store it is possible to use B401 - a preparation of Bacillus thuringensis to treat the combs.
Are there other species of wax moth?
The moth, Aphomia sociella is known as the “bee moth” and is very similar to the greater wax moth. The body and forewings are a reddish brown and the forewing of the female moth, has a distinct dark spot on it. This sub-species is attracted by the scent of bumble bee and wasp species nests, feeding on the waste products of the larvae, as well as dead adults. Larvae reach 24–30 mm in length and become distinctly yellow in colour. They create tunnels of silken thread throughout the nest and as a result, bumble bees may abscond their nest during high infestations.