Diseases of bees / Ministry of Agriculture and Fisheries.

Date:
1948
Catalogue details

Licence: Public Domain Mark

Credit: Diseases of bees / Ministry of Agriculture and Fisheries. Source: Wellcome Collection.

    12/36 (page 8)
    Symptoms. The cappings are not affected by the death of the larvae within the cells, but they are afterwards removed by the bees and it is then that the chalky-white appearance of the dead brood can be seen by the bee-keeper (Fig. 8). The larvae are transformed by the growth of the mould into white objects which look like small mummies. These fill the cells completely at first and have a rather spongy or rubber-like consistency. Later they shrink and become tough and rather fibrous. At this stage they are quite loose in their cells and can easily be removed by shaking the comb. Sometimes the mummies lose their white appearance and assume a greenish-brown or black. colour; this is due to the formation by the mould of cysts containing spores, but it happens only when both male and female spores have germinated in the same larva to form growths of both sexes. Spread. Chalk Brood must be regarded as a contagious disease and it can be spread by the transfer of affected combs from one colony to another. The spores of the mould can, however, remain in a hive without doing any harm, becoming active only when conditions are suitable for them to develop. In well-kept apiaries these conditions either do not occur, or exist only temporarily, so that the probability of the disease becoming established is remote. Treatment. In mild cases the colony may overcome the attack without any assistance from the bee-keeper. ‘With more serious attacks the worst combs may have to be destroyed and the bees transferred to a fresh hive fitted with clean drawn comb or foundation. The old hive should then be scraped clean and treated with a blow-lamp, as for Foul Brood (see page 6) before being used again. If the disease persists after the bees have been transferred, it is recommended that the colony be requeened with a queen of a different strain, whose progeny may be able to overcome the attack of the mould where the others failed. Dampness in the hive should be avoided, and any affected colonies which are exposed to damp conditions should be removed to a drier situation. Strong colonies with vigorous queens, kept in sound, well ventilated hives are the best form of defence against the disease. STONE BROOD This disease is caused by a mould belonging to the genus Aspergellus. The ‘mould attacks the brood transforming the larvae into hard stone-coloured ‘objects which are found lying in open cells. Adult bees may also be attacked and killed by the mould. The disease is rare in this country, only one case having been definitely recorded. A sample comb from any suspected case ‘of the disease should be sent for examination without delay (see p. 25). Since some of the AsPergellus moulds can cause trouble in the respiratory passages ‘in man, care should be taken not to inhale any of the dust (spores) with which ‘the dead brood may be covered. ADDLED BROOD This is a common disease which at first sight may be mistaken for American Foul Brood, since it is the sealed brood which is affected, and moist, sunken, or perforated cappings are usually to be seen. The dead brood maintains its shape and outline to some extent, however, and the contents of the affected cells are never ropy.