3 Department Circular 33^, U. S. Dept. of Agriculture 



worker bees and that if larger numbers occur it is almost exclusively 

 on queens. In Maryland two Braula have not been observed on a 

 single worker and they are rare on the queens, except under the 

 conditions previously described. 



PERCEPTION OF LIGHT BY BRAULA 



The specific name coeca was given this species by Nitzsch on the 

 assumption that it is blind. Miiggenburg {29) points out that — 



it is not blind, for despite the previous statements, it has two small eyes which 

 lie above the antennae. From their situation these eyes represent the com- 

 pound eyes of the Diptera. Their dioptic apparatus is only very slightly devel- 

 oped. The chitin of the head covering over the place in question is thinner and 

 transparent * * * and shows no trace of facet formation. Ommatidia are 

 not found under the imperfect cornea. From sections we perceive, as in early 

 developmental stages of insect eyes, a mass of hypodermal cells which show a 

 tendenc}' to radial arrangement. Pigment is not present. However, a thin 

 optic nerve extends to this rudimentary eye from the supra-oesophageal ganglion 

 which increases near its connection with the same to a small ganglion. 



Massonnat (28) describes this eye structure in still more detail 

 and figures the various internal parts, but, unlike Miiggenburg, 

 he claims to find traces of pigment. Timm (36) also describes the 

 presence of eyes. Von Buttel-Reepen (37) pointed out to beekeepers 

 the incorrectness of the statements that Braula is blind, but this 

 same error has since been repeated in more recent beekeeping papers. 

 No physiological work has been reported to determine whether 

 Braula actually responds to light stimuli. 



REMEDIES 



It is commonly stated in European beekeeping literature that 

 Braula occurs in weak and badly managed colonies, especially in those 

 the hives of which are not kept clean. If these statements are 

 correct, preventive measures would seem to be of far greater im- 

 portance than methods for the removal of Braula. Various methods 

 are given for its removal. An early method was to pick them from 

 the queens by means of a feather, some suggesting first dipping it in 

 honey to cause them to adhere well. Arnhart (2) uses small pointed 

 sticks dipped in honey in the same manner. It is also recommended 

 (6) that the queen be removed from the colony and gently smoked 

 with tobacco smoke, which causes the stupefied Braula to drop off, 

 after which they may be destroyed, and since she will probably 

 collect more when returned to the hive, it is usually recommended 

 that this be repeated at intervals. This method has its faults, 

 since the smoking of the queen may cause the bees to ball her when 

 returned. The placing of a small baoj of napthalene on the bottom 

 board of the hive is said (11, 19, 25) to cause the insects to drop 

 from the bees to the bottom board, from which they should then be 

 removed before any of them recover. Smoking wdth saltpeter or 

 Lycopodium, old methods for stupefying bees, have been recommended 

 (9), as well as oil of turpentine (19) on a cloth on the bottom board, 

 carbolic acid (V^) similarly used, and incense powder (11), these all 

 being used because Braula apparently succumbs to such fumigation 

 before the bees do. Zander (39) , however, points out that naphtha- 

 lene may not only dislodge the Braula but may also drive the bees 



