22 



BULLETIN 804, V. S. DEPABTMENT OF AGRICULTURE 



there must be a difference between the food which larvae younger 

 than approximately 3 days old receive and that fed to older ones. 

 Otherwise the younger larvae would also show the pink coloration. 

 Von Planta (9) by chemical analyses, of questionable exactness, how- 

 ever, makes a division in the feeding of the larvae at the age of 4 

 days, at which time the high protein and low sugar content change 

 to lower protein and higher sugar content. These analyses would 

 tend to coincide with the above observations, only it is probable that 

 the change begins earlier. 



Additional data upon this subject are recorded in Tables II and III, 

 although the observations were primarily for another purpose. In 

 order to obtain further information relating to a possible difference 

 in resistance to disease between Italian and hybrid bees, a careful 

 record was made of the time when eggs were first noted in empty 

 combs after the infection of the colony and when larvae first showed 

 disease thereafter. In the case of comb Special No. 2, the eggs were 

 laid by an Italian queen in a healthy colony and then placed in a 

 diseased colony. Colonies F, A, and I were of Italian stock while 

 colonies G, H, and J were hybrid. In the recurrence of disease all 

 were given new Italian queens. As has been mentioned before, as soon 

 as the bees of the new Italian queens emerged in sufficient numbers 

 the disease disappeared. 



Table II 



THE FIRST APPEAEANCE OF DISEASE IN COMBS IN WHICH EGGS WERE LAID AFTER 

 THE COLONY WAS INFECTED 



