176 PLANKTON OF WISCONSIN LAKES 



Hemiptera. The sample of Hemiptera contained representatives of 

 several genera ; nearly haK of the material consisted of young Belosto- 

 ma, while about a quarter of it was made up of Notonecta and Corixa. 

 The remainder consisted of Nepa, Naucoris, and Kanatra, with a few 

 individuals belonging to still other genera. This sample yielded a much 

 larger percentage of nitrogen than the Gyrinids; with the ash in- 

 cluded, only four samples of animal material gave a larger percentage 

 of nitrogen than these Hemiptera, but on an ash free basis the percent- 

 age of nitrogen in the latter is exceeded by that in seven other animal 

 samples. 



This sample of Hemiptera yielded a relatively small percentage of 

 fat or ether extract ; only one other insect sample shows a smaller per- 

 centage, namely, Chironomus tentans, while that of Sialis is more than 

 twice as large and that of the Gyrinids is n^ore than four times as large. 

 The percentage of crude fiber is relatively high in the Hemiptera, being 

 exceeded by only two other insect samples. The nitrogen free extract 

 is smaller than in five of the other insect samples and larger than in 

 three. 



The percentage of ash in the Hemiptera material is nearly four times 

 as large as that in the Gyrinids, but it is fairly low in comparison with 

 the other insect samples. 



McHargue^^ analyzed samples of grasshoppers (Melanoplus) and 

 June bugs (Lachnosterna). He states that 75.28 per cent of the dry 

 weight of the grasshopper material consisted of crude protein and that 

 the percentage was somewhat larger in the June bugs, no definite per- 

 centage being given for the latter form. This author does not state, 

 however, whether any correction was made in the total nitrogen for 

 that part which enters into the composition of the chitinous coverings 

 of these insects. If such a correction has not been made, the percentage 

 of crude protein indicated by McHargue is larger than it should be; 

 a little more than 6.0 per cent of the dry weight of chitin consists of 

 nitrogen. 



The percentage of crude protein in the grasshopper material as given 

 by McHargue is more than twice as large as that in the Gyrinids and it 

 is 8.16 per cent larger than the maximum in the aquatic insect samples 

 shown in table 49. The grasshoppers yielded only 7.21 per cent of ether 

 extract, or less than the minimum of these aquatic insects ; the former 

 contained 5.61 per cent of ash and only three of the ten insect samples 

 analyzed in this series fell below this percentage. The main constitu- 

 ents of the grasshopper ash consisted of silica (0.6 per cent), potassium 

 oxide (1.2 per cent), and phosphorus pentoxide (1.19 per cent). 



"Jour. Agric. Eesearch, Vol. 10, 1917, pp. 633-637. 



