268 



AMERICAN BEE JOURNAL 



July 



while examining atrophied muscle 

 fibres from the thorax of a diseased 

 bee noted a number of oval bodies 

 within a fragment of a tracheal tube 

 included in the same preparation. 

 These bodies proved to be acarine lar- 

 vae. 



Examination of the thoracic tra- 

 chea of other crawling bees showed 

 certain of the major tracheae to be ex- 

 tensively obstructed by mites in all 

 stages of development, from ova to 

 adult forms. 



An examination was made of 150 

 bees from several diseased stocks and 

 the parasite was found in every case. 

 One hundred apparently healthy bees 

 from apparently healthy stocks were 

 also examined and the parasites were 

 absent in 95 per cent. 



With these data to hand, the writer 

 reported his observations to his col- 

 leagues and advanced the theory that 

 this parasite was the cause of Isle-of- 

 Wight disease. 



At the same time he learned that a 

 solitary mite had been seen in the 

 trachea of an apparently normal bee 

 by Dr. Rennie and Miss Harvey 

 in the previous December, but no 

 causal relationship was then sus- 

 pected. 



Dr. Rennie, Miss Harvey and the 

 writer then commenced a routine ex- 

 amination of a large number of dis- 

 eased and healthy stocks involving 

 the examination of upwards of 3,000 

 individual bees. 



The results of this work may be 

 summarized as follows: 



1. The mites were found present 

 in every stock exhibiting symptoms 

 of the disease, and in every crawling 

 bee. 



2. The mites were absent in the 

 great majority of apparently healthy 

 bees from apparently healthy stocks 

 (approx. 80-90 per cent of those ex- 

 amined between May and October, 

 1920). 



3. In approximately 35 per cent 

 of seemingly healthy stocks derived 

 from the British Isles, a varying, al- 

 though usually low, percentage of in- 

 fection was present. A number of 

 these stocks kept under observation 

 later developed the disease. 



4. No mites were discovered in 

 samples of bees sent from the Conti- 

 nent. 



The results, therefore, strongly 

 support the view that the mites are a 

 "sine qua non" of the disease. 



Dr. Rennie, after a systematic 

 study of the parasite, has relegated it 

 to the genus Tarsonemus, giving it 

 the specific name, T. Woodi (nova 

 spec.) in token of gratitude for the 

 interest and support of Mr. Wood 

 throughout the investigation. Dr. 

 Rennie has further made progress 

 with the study of the life history of 

 the mite. 



The writer took up the pathology 

 of the disease. 



The parasites were found to enter 

 the bee through one or both of the 

 first pair of spiracular orifices and 

 apparently through these alone. They 

 remain located in the system of major 

 tracheae and air sacs of the anterior 

 moiety of the thorax and in the ves- 

 sels of the head — these latter being 



less frequently invaded. No mites 

 have been found in the respiratory 

 system of the abdomen. 



In the earlier stages of the attack 

 the microscope reveals the almost col- 

 orless ova and embryos lying within 

 the lumen of the otherwise normal 

 trachea. The parent mites may usu- 

 ally be found in their vicinity. 



As development proceeds, the tra- 

 cheal lumen becomes markedly ob- 

 structed and the wall becomes en- 

 crusted and bronzed with fsecal de- 

 posits. In the later stages this color 

 generally deepens to black. 



The aff'ected tracheae now appear 

 deep brown or black to the eye. They 

 have lost their elasticity and have be- 

 come hard and brittle. This is the 

 condition found in the majority of 

 bees ci'awling from the disease. 



In a high percentage of Isle-of- 

 Wight "crawlers" atrophic changes 

 of the thoracic muscles of flight oc- 

 cur. As a rule only a few fibres show 

 marked changes. The aft'ected fibres 

 are white, thread-like and brittle, 

 thus contrasting with the flaccid grey- 

 ish-yellow normal fibres. There is 

 advanced wastage of the fibrillar sub- 

 stance, loss of fluid and condensation 

 of the granules of the fibre. The 

 atrophied fibres are frequently re- 

 duced to one-half the normal width 

 during relaxation. It seems probable 

 that such fibres are dead ; they are 

 certainly functionless. 



Occasionally the black spots de- 

 velop in the muscle fibres of infected 

 bees, but their causation is not yet 

 definitely elucidated. 



The examination of the alimentary 

 and other systems has revealed no 

 other characteristic lesion associated 

 with the disease. 



The primary eff'ect of the mites 

 upon the bee has a double aspect. The 

 parasite living and developing at the 

 expense of the body fluids of the bee 

 must threaten nutrition. Possibly, 

 too, they are actually venomous. The 

 actual importance of this active in- 

 jury is, however, a matter of surprise. 



In the second place, there is the 

 partial or complete obstruction of 

 certain of the thoracic tracheae by the 

 parasites and their products. The im- 

 portance of this passive factor is 

 much more readily estimated. In the 



great majority of crawling bees the 

 efl'ective lumina of certain major tho- 

 racic trachese are reduced to the la- 

 cunae between the closely packed 

 parasites and the air which filters 

 through must be depleted of oxygen 

 by the mites themselves. The organs 

 which are supplied by such ti-acheae 

 must suflfer from oxygen starvation. 



Among the organs of which the re- 

 spiratory exchange is thus endan- 

 gered are the thoracic muscles of 

 flight and the cerebral ganglia. 



With this in view, a series of con- 

 trolled experiments were made upon 

 normal bees in which one or both of 

 the first pair of spiracles had been 

 closed with wax. A condition of 

 crawling closely simulating Isle-of- 

 Wight disease was produced, and in a 

 few days muscle atrophy identical 

 with that found in diseased bees ap- 

 peared in many cases. 



These experiments support the 

 view that mechanical blocking of the 

 tracheae is a factor of great import- 

 ance — perhaps capable in itself of oc- 

 casioning all the symptoms by which 

 we are wont to recognize the disease. 



Through the impairment of the re- 

 spiratory exchange of the thoracic 

 musculature and the cerebral centers 

 the power of flight is lost, and with 

 loss of flight a series of secondary 

 conditions arise. The fseces, normal- 

 ly voided on the wing, are retained 

 and accumulate, compressing the ab- 

 dominal air sacs — another blow at the 

 respiratory function. 



It is probable that toxins are ab- 

 sorbed from the stagnant gut and 

 that excretory stasis in the Malpigh- 

 ian tubules is reflected back upon the 

 body of the bee. 



Once the flightless bee leaves the 

 hive, unable to return, it perishes 

 from cold and starvation. Should it 

 remain it is faced with the condition 

 of functional stagnation which can- 

 not be infinitely maintained. 



It is impossible in this condensed 

 paper to touch on several important 

 matters, as for instance the transmis- 

 sion of the disease and its seemingly 

 insular distribution. Certain details 

 have been omitted, together with 

 such matters as the special character- 

 istics and life history of the parasite, 

 of which others can speak with 

 greater authority than the writer. 



It would now seem advisable to re- 

 place the rather meaningless term 

 Isle-of-Wight disease by the term 

 "Acarine" (or mite) disease. This 

 is not likely to lead to confusion for, 

 though several species of mite are 

 known to occur on bees, T. woodi 

 alone appears to be associated with 

 pathological phenomena. 



Scotland. 



A. The acarine mite. B. Fourth leg of fe- 

 male. C. Fourth leg of male. 



PEDDLING HONEY 



By Patrick J. Murphy 



Interesting indeed is the article in 

 the January issue, from Mr. Wesley 

 Foster, concerning marketing of 

 honey and the profits taken by honey 

 peddlers. 



The producer forgets that the per- 

 centage of profit that the average 

 vender of honey takes is less by far 



