﻿BULLETIN 14, U. S. DEPARTMENT OF AGRICULTURE. 

 Table III. — Migratory habit of housefly larvse; experiment No. S. 



Date. 



Larvae 

 collected 

 from pan. 



Flies 

 caught 

 in traps. 



Date. 



Larvae 

 collected 

 from pan. 



Flies 



caught 



In traps. 



1913. 

 Nov. 14 

 15 

 16 

 17 

 18 

 19 

 20 

 21 

 22 

 23 

 24 

 25 

 26 



162 



656 



1,950 



2,650 



1,240 



40 



C 1 ) 



12 





















1913. 



Nov. 27 



28 



29 



Dec. 1 



2 



3 



4 



5 



6 



7 





3 

 2 

 2 

 2 

 8 

 5 

 6 

 15 

 10 

 3 























7 

 

 

 

 

 4 



2 i 













6,710 



69 





1 Collected on following date. 



Out of a possible total of 6,779 there were destroyed 6,710 larvse, 

 that is to say, about 99 per cent were destroyed before they reached 

 the pupal stage. 



The percentages obtained in these experiments clearly demonstrate 

 the habitual nature of the migration. They also demonstrate the 

 efficiency of the maggot trap which is designed to take advantage of 

 this mode of action. The question immediately arises whether the 

 trap which appears so successful in an experimental way on a small 

 scale can be adapted to the handling of manure in a practical way and 

 on a large scale. Every consideration points to the probability that it 

 can and that it will afford "an additional weapon of great value." 

 However, the final verdict as to the value of the maggot trap must 

 wait upon the solution of certain practical problems. To point out 

 some of these here is to suggest lines for further investigation. 



(1) In the first place, there must be determined what form, size, 

 and construction of trap will give the best results. The answer to 

 this will depend largely on the particular conditions obtaining at any 

 given stable, such as the amount of manure produced daily, the 

 arrangements for drainage, etc. It will also depend on the answer to 

 the following problems : 



(2) How deeply may manure be heaped in a trap without inter- 

 fering with the migration ? It will probably be found that the depth 

 will make little difference, provided that the manure is kept moist,- 

 and provided that avenues of escape are afforded at the sides as well 

 as at the bottom. The importance of providing a way of escape at the 

 sides was not taken into consideration by Levy and Tuck in their 

 preliminary experiments. 



(3) How long must manure be kept in a maggot trap before it is 

 entirely free from larvse? This is a very important question from a 

 practical standpoint, and one will find scant suggestion as to the 

 answer in the literature on the life history and habits. The housefly 



