80 



" Isle of Wight " Disease of Bees. 



[Apr., 



country, and it was found that every stock reported by reliable 

 bee-keepers, or certified by the investigators themselves, as 

 suffering from the disease, harboured this parasite, while 



Nosema Apis " was not always present. Similarly, every indi- 

 vidual bee known to be suffering from this disease from its stock 

 history and individual symptoms, was also found to contain these 

 parasites, and to exhibit the internal disorders which caused the 

 disabhng symptoms. The investigators stated that they were 

 now able to diagnose the disease in its earhest stages, while the 

 bees were capable of flying and foraging. Infection appeared 

 to occur mainly in the hive, the conditions of the cluster making 

 this comparatively easy. In support of this theory, mites have 

 been obtained from the outside of the bee apparently on their 

 migratory passage. 



In the light of this discovery much that was puzzling in the 

 symptoms of the disease appears to be cleared up. The mite 

 infests the trachea of the thorax only, entering by the spiracles, 

 and breeding takes place here, until eventually the trachea 

 becomes partially or wholly obstructed. In the latter case the 

 bee dies at once, w^hile in the former, being unable to fill the 

 air sacs which permit of flight, it is reduced to crawling. 

 In such cases the faeces are not evacuated, as normally this is 

 accomplished w^hen the bee is on the wing, and hence arises the 

 congested condition of the bowels, and the consequent staining 

 of the combs, hive front, and alighting board. 



Interesting experiments were carried out by blocking up the 

 thoracical spiracles of the bee with wax, and by this means all 

 the usual symptoms of " Isle of Wight " disease were produced. 

 Tests were also made on young bees which were hatched from 

 combs in an incubator and from which all the adult bees had 

 been previously removed. Out of the 157 young bees that were 

 examined only one was found to be affected with " Tarsoneme " ; 

 this may have remaired on the comb, and entered the bee after it 

 had emerged from the cell, so that it is reasonable to suppose 

 that young bees are not affected. This supposition is further 

 strengthened by the fact that in the past, stocks apparently have 

 been cured, and have given surplus honey by making an arti- 

 ficial swarm from the affected stock; the swarm, consisting of 

 all the old infected bees being destroyed, and the young and 

 hatching bees allowed to carry on the work of the hive. 



Many bees from different countries outside Great Britain 

 have been examined, and so far " Tarsonemus " has not been 

 found in them. All the evidence obtained points to this parasite 

 in bees being peculiar to this country. 



