A NUTRITIONAL STUDY OF INSECTS 



23 



Adults placed on media from which sugars were absent died after 

 one to four days, whereas those placed on media containing Pas- 

 teur's solution lived for a much longer time. The larvae on the 

 nucleoprotein alone live for several days, but do not increase in 

 size and are not very active. It may be that a sweet taste is 

 necessary to stimulate them to take food or it may be that carbo- 

 hydrates are necessary to furnish energy "fuel." The larvae on 

 nucleoprotein and carbohydrates grow slowly at first, but quite 

 rapidly after reaching a length of 3 to 4 mm. This may be due 

 to the rather large size of the nucleoprotein crystals or to the depth 



^e f/3 ^ays . 



P— Pupafio/]. 



J7.= Veaii of-/arya 



l|2. l|5 l|* 1|S ,|fe ,|7 l|e l|9 z|0 2j. 2|2 2J3 z|4 z\i z\c. z\r 



■'I «l H 



Fig. 7 Larval growth on yeast nucleoprotein. 1, 2, 3, 4, 5, yeast nucleopro- 

 tein, sugars, and salts; 6, 7, yeast nucleoprotein and tap- water. 



to which they sink in the agar. In figure 7 are shown the curves 

 of growth on these media. Curves 1 to 5 show the rapid growth 

 on yeast nucleoprotein, sugars, and salts and curves 6 and 7 show 

 the slow growth or diminution on nucleoprotein alone. One 

 curve of growth on yeast nucleoprotein and sugar, etc., given (fig. 

 4, curve 6) in the same figure with curves for yeast media, shows 

 that larvae grow more rapidly on yeast nucleoprotein and sugar 

 than on 2 per cent but less rapidly than on 3 per cent yeast. It 

 must be remembered that mechanical questions of ingestion and 

 the question of taste or olfactory preference may largely affect 

 the amount of material eaten and therefore the rate of growth. 



