26 CIRCULAR 392, U. S. DEPARTMENT OF AGRICULTURE 



females crawl out and enter the tracheae of other bees within the 

 hive, thereby transmitting the disease. Acarine disease is thought 

 to be transmitted from diseased to healthy colonies by the drifting 

 of infested workers, or drones, or by robber bees. This disease may 

 also be transmitted by requeening a colony with an infested queen. 



SYMPTOMS 



Infested bees are unable to breathe normally, and the walls of the 

 tracheae and other tissues are injured. Bees that contain large 

 numbers of mites are unable to fly and are known as crawlers. 

 Crawlers usually leave the hive, when the weather is favorable, and 

 die outside. When large numbers of infested bees crawl from the 

 hive at about the same time, the condition is known as mass crawling. 



Bees often continue to work for weeks after they have become 

 infested by mites, and acarine disease may be well advanced in a 

 colony before symptoms are noticeable. The most commonly rec- 

 ognized symptoms are crawling and the loss of ability to fly. Crawl- 

 ing may come on gradually when the disease spreads slowly within 

 the colony, or it may develop rapidly and result in mass crawling. 

 After mass crawling has occurred, the colony is freed of most of 

 the diseased bees and may appear to recover temporarily. Mass 

 crawling often follows a period of unfavorable weather. Crawling 

 is frequently accompanied by retention of feces, swollen abdomens, 

 and unjointed wings. 



DIAGNOSIS IN THE APIARY 



In healthy bees the tracheae are always pure white. In heavily 

 infested bees the tracheae become bronzed or blackened in irregular 

 spots. The presence of these spots is used as a symptom in diagnosis. 

 With the aid of a lens that magnifies 6 or 8 times, the dark-colored 

 spots can be distinguished. They may be few in number, or there 

 may be so many that the trachea appears black. 



In making examinations for acarine disease in the apiary it is best 

 to use crawlers. The tracheae of bees killed by other disorders often 

 become black after a few days, while infested bees that are able to 

 fly may not show the discolored spots on the tracheae. The head 

 and front part of the thorax (prothorax) with the first pair of 

 legs should be cut away and discarded. This will bring into view 

 the first pair of breathing tubes, which are the ones most likely to be 

 discolored if acarine disease is present. 



Septicemia 

 cause 



Septicemia is a slightly infectious disease of adult honeybees. It 

 is caused by growth in the blood of infected bees of a bacterium 

 known as Bacillus apisepticus. This bacterium may be present in 

 colonies, in the soil near infected colonies, or in water that has been 

 in contact with bees killed by septicemia. Bees that become wet 



