DIAGNOSING BEE DISEASES IN THE APIARY 29 



By pressing the abdomen between the fingers, an increased firmness 

 can sometimes be noticed at the time of death, bnt it is most notice- 

 able a few hours later. It is unsafe to depend upon this symptom 

 longer than about 1 or 2 days after death, since nonpathogenic fungi 

 may produce similar symptoms in bees killed by other disorders. 



Paralysis 

 cause 



The so-called paralysis of adult honeybees appears to be a slightly 

 infectious disease that causes weakness, trembling, and death of the 

 affected bees. The cause of paralysis has recently been proved, at 

 the laboratory of the Division of Bee Culture, to be a filterable virus, 

 too small to be seen under the usual microscope. 



IMPORTANCE 



Paralysis of honeybees is a widely distributed disorder, but it 

 causes greater losses in warm than in cold climates. Affected 

 colonies usually recover after a short time, but in some cases the 

 disorder continues throughout the season. In the Northern States it 

 usually disappears or remains confined to one or a few colonies 

 within an apiary, but in the South it sometimes spreads and causes 

 considerable loss. The losses range from a few bees in mild cases to 

 most of the bees of the affected colonies in malignant cases. 



SYMPTOMS 



Inasmuch as the appearance of the sick and dead bees is not always 

 the same, there seems to be a difference of opinion regarding the 

 symptoms of paralysis. Other disturbances of adult bees may also 

 have been mistaken for paralysis. 



During the early stages of paralysis, affected bees remain on the 

 combs and cannot be distinguished readily, except that the healthy 

 bees often tug and pull at them excitedly. The sick bees make but 

 little effort to defend themselves. Sometimes they attempt to escape 

 by crawling away. Finally, they leave the hive and die outside or 

 crawl into a corner of the hive or onto the top bars, where they remain 

 until death occurs or until they are carried out of the hive by the 

 healthy bees. Some affected bees die within a day or two after the 

 symptoms have become noticeable, others linger for more than a week, 

 while still others recover. The abdomens of the sick bees are usually 

 of normal size but often appear swollen or, less frequently, shrunken. 

 Some of the sick bees retain their hairs until they die, whereas others 

 become partially or entirely hairless, probably because their hairs 

 are pulled out by healthy bees. Loss of hairs is accompanied 

 by a darkening of the abdomen and thorax and a shiny or greasy 

 appearance. 



The most charasteristic symptom of paralysis is weakness and a 

 trembling or shaking movement of the body and wings, frequently 

 accompanied by hairlessness and sprawled legs and wings. Sick 

 bees that are motionless will sometimes show the trembling move- 

 ments when disturbed. Some of the symptoms given here for paraly- 



