240 Anna Maurizio 



described as follows. During the warm season the young bee 

 feeds for the first few days of its life on pollen, developing its 

 pharyngeal glands. With the commencement of brood- 

 rearing the reserves are used up and the bee ages physio- 

 logically, thus becoming a short-lived summer flying-bee. 

 However, if for any cause brood-rearing is limited (e.g. due to 

 a queenless colony, swarming, prolonged rain, etc.), or com- 

 pletely omitted, the pharyngeal glands will remain fully 

 developed, the fat body will be formed and the lifespan thus 

 increased. In the free-flying colony during the active season 

 it is possible to produce experimentally such a generation of 

 physiologically young, long-lived bees. 



When brood-rearing is naturally limited and at the same 

 time intensive pollen-feeding takes place, a long-lived winter 

 bee with large body reserves, fully developed pharyngeal 

 glands and a many-layered fat body is produced in late 

 summer or autumn ; the bee is thus enabled to overwinter and 

 to rear the first brood in spring. During the winter the bee 

 feeds almost entirely on sugar and therefore it seems that the 

 substances (protein, glycogen and vitamins) necessary to 

 survive winter are drawn from the reserves built up in the fat 

 body. A similar kind of overwintering is known of other solitary 

 insects such as Anopheles, Culex, Lasiopticus, Epistrophe, Ips 

 typographus, etc. (Buxton, 1935; Kuhn, 1949; Schneider, 1947, 

 1948; Wigglesworth, 1950). 



(3) It appears that the lifespan and physiological condition 

 of bees in free-flying colonies depend greatly on nutrition and 

 brood-rearing. Long-lived bees always appear in a colony 

 where a rich supply of pollen is available and where little or 

 no brood is in need of nursing. In our climate long-lived bees 

 appear in autumn and winter, but under diff'erent climatic 

 conditions this may occur at different times or fail to take 

 place. Thus the physiological condition of the "summer" and 

 "winter" bee does not depend on a certain season, but can 

 be promoted at any time as a reaction to external conditions 

 essential to life. 



