DIAGNOSING BEE DISEASES IN THE APIARY 25 



lap, and usually a diagnosis cannot be made in the apiary. There 

 are a few dependable symptoms of diseases of adult bees, however, 

 which can be recognized without a miscroscope, and with good 

 samples it is sometimes possible to make a diagnosis in the apiary. 



NOSEMA DISEASE 

 CAUSE 



Nosema disease is caused by a minute, single-celled animal parasite 

 known as Nosema apis. Adult workers, drones, and queens are 

 affected. Spores of N. apis enter the body of the adult bee with food 

 or water. They germinate within the stomach and attack the 

 tissues which line the stomach or mid-intestine, with varying 

 harmful effects. 



IMPORTANCE 



Nosema disease is wide-spread and under conditions favorable for 

 its spread causes extensive losses of adult bees. When accompanied 

 by dysentery brought on by long winter confinement, the disease may 

 spread rapidly within infected colonies and result in the death of 

 the colonies late in the winter or in the spring; or heavy losses 

 from Nosema disease may continue for weeks after the bees have 

 been flying freely and dysentery has subsided. Infected bees usually 

 perform^ their normal duties until they are too weak to continue. 

 The shortened life of infected bees weakens or kills the colony. 



SYMPTOMS SHOWN BY THE COLONY 



The first noticeable symptoms shown by a colony heavily infected 

 by Nosema apis are increasing restlessness of the bees and a weaken- 

 ing of the colony. When only a small number of bees are infected, 

 the loss may be so gradual that it is not noticed. At other times the 

 death rate among adult bees is very high, and the colony dwindles 

 rapidly. The queen usually is among the last handful of bees to 

 die. Nosema disease may appear annually at about the same time. 

 During any time of year, however, colonies with bees infected by 

 N. apis may be foimd that show no noticeable loss. 



SYMPTOMS SHOWN BY INFECTED BEES 



In the individual bee the symptom most commonly observed is 

 inability to fly more than a few yards without alighting. Many 

 bees will be seen crawling on the ground, on the bottom board, at 

 the entrance,* and on the top of frames when the cover is removed. 

 Sometimes infected bees crawl actively long distances from the hive, 

 or they may crawl up blades of grassi in an effort to fly. At times 

 they collect in small groups on the ground in front of the hive. 



ft is mostly the older workers that are killed, although drones, 

 queens, and young workers may be attacked. At times the disease 

 seems to be aggravated by periods of cold, damp weather, particu- 

 larly in the spring when the bees cannot fly freely. 



The legs of affected bees may be dragged along in crawling, as 

 if paralyzed; and the rear wings may be unhooked from the front 



