NOSEMA-DISEASE. 49 



While the colony symptoms may justify a very strong suspicion that 

 the disease is present, an examination of the stomachs from adult bees 

 of the colony is necessary in making a definite diagnosis. The selec- 

 tion of the proper sample for examination is important. In choosing 

 samples it is advisable to take such bees as are most likely to show a 

 high percentage Nosema-infected. Young workers, old shiny ones, 

 and drones are, therefore, to be avoided. Workers from the field are 

 naturally to be preferred. As bees carrying pollen are most readily 

 recognized as being field bees, these are the ones usually sought. 

 Sometimes it is more convenient to take bees carrying honey or water. 

 Next to the field bees, preference should be had for bees from among 

 those about the entrance of the hive. During the colder seasons of 

 the year it is often necessary to take the samples from the brood- 

 combs. 



Ten bees from a colony constitute a satisfactory sample as a rule. 

 Ordinarily these are taken at the entrance with forceps. They 

 are killed by pinching the thorax. All of the bees of the sample 

 should be examined. 



In removing the stomach for examination the bee is held by the 

 thorax between the thumb and index finger of one hand and with a 

 pair of forceps held in the other the tip of the abdomen is seized and 

 pulled gently. By this method the organs of the alimentary tract 

 (PL I) forward to and including the stomach are easily obtained. 

 Occasionally the proventriculus and honey sac are also removed by 

 this procedure. The stomach is the most prominent of the organs 

 removed and the one that is most readily recognized. 



If the stomach upon removal appears swollen and lighter in color 

 than a healthy one, Nosema infection may be suspected; if it is chalk- 

 white and easily torn, infection is very probable; should the tissues 

 of the organ when crushed be milky in appearance, infection is 

 practically certain. Usually the gross examination is sufiicient for 

 a definite diagnosis of the disease as encountered in nature. Some- 

 times it is desirable however, to have such a diagnosis confirmed by a 

 microscopic examination of the crushed tissues of the stomach. This 

 is often the case in experimental studies. 



If infection is present in a bee the oval ghstening spores of the 

 parasite (fig. 4) usually will be found in very large numbers upon a 

 microscopic examination of the crushed tissues of the stomach. No 

 staining is needed. Addition of water to the mount is not necessary 

 but it improves the preparation, permitting the spores to be seen more 

 distinctly. Stomachs which become dry, after their removal and be- 

 fore the examination is made, can be used readily by the addition of 

 water. 



