DESTRUCTION OF FLY LARVAE IN HORSE MANURE. 19 



F.) in from five to seven days after the experiment was started. At 

 the same time the borax-treated piles reached their maximum of 58° 

 to 63° C. (136.4° to 145.4° F.). Even where one-eighth pound of 

 borax was used the temperature was slightly suppressed, as it reached 

 only 61° C. (141.8 F.). This effect, however, may have been due to 

 the borax preventing the growth of organisms which produce fire- 

 f anging. The effect of borax in entirely preventing this condition has 

 been reserved for a future investigation. However, it was found that 

 in three cases the control piles showed evidences of firefanging and 

 the presence of a white powdery mold in the interior. This condition 

 was never found in the borax-treated piles. After attaining a maxi- 

 mum, the temperature of all the piles declined rapidly. The treated 

 ones continued lower than the controls. 



One manure pile treated with 5 pounds of calcined colemanite 

 showed a steady decline in temperature from the beginning of the ex- 

 periment. The bactericidal effect of this large dose is further shown 

 by a comparison of the bacterial count obtained from a sample of 

 this pile and that of the control ; a decrease of 64 per cent in the num- 

 ber of bacteria occurred. 



The data of the borax-treated manure are recorded in Tables V and 

 VI. The open-pile experiments, which are recorded in Table V, show 

 marked variations in numbers of bacteria, but whether this is due to 

 a variation in the penetration of the borax because of different nat- 

 ural factors, or because the samples were not representative of the 

 pile, although taken in the usual manner (see page 5), can not be 

 stated at this time. There is a reduction in the number of bacteria 

 in Series J, Nos. 1 and 2, and Series L, Nos. 1 and 2, where colemanite 

 was used. There are marked increases in Series I, Nos. 1 and 2, and 

 Series K, Nos. 3 and 4. In Table VI, where the results are recorded 

 for the manure experiments made in cages, an increase in the number 

 of bacteria is seen in all the borax-treated samples. 



The manure from the open-pile experiments, Table V, indicates an 

 increase of water-soluble nitrogen and ammonia in the borate-treated 

 samples. The reaction of the water extract is increased in all of these 

 cases. Further, in four of the open-pile experiments nitrites and 

 nitrates were both found. In no case did the control manure give a 

 reaction for nitrites or nitrates. The presence of nitrites and nitrates 

 in the borax-treated piles is very interesting and if it is obtained in 

 all cases where the borax-treated manure has been allowed to stand 

 for several weeks a strong argument will be presented for its use in 

 addition to the effective larvicidal action which it is seen to possess. 

 There are considerable variations in the water-soluble nitrogen and 

 ammonia results for the open-pile experiments as well as for the 

 bacterial counts as noted on page 6. 



