10 BULLETIN 14, IT. S. DEPARTMENT OF AGRICULTURE. 
(4) The disposal of the maggots is another practical consideration. 
If the larvae were allowed to drop to the ground they would burrow 
into it to pupate there and nothing would be gained. It would be 
necessary to have some sort of vessel, e. g., a concrete basin, beneath 
the trap. This should have vertical sides and contain an inch or 
more of a weak disinfectant or of water covered with a film of oil. 
If such a basin were connected with a sewer or cesspool the maggots 
collecting in it could be flushed out each week without the necessity 
of handling them in any way and without any offensive decomposi- 
tion. 
That the maggot trap possesses certain advantages is obvious and 
ought to lead to many attempts to develop it along practical lines. 
Cheapness would be one of its strong points. Practically the only 
cost would be the initial one for the construction of the trap and of 
a basin or receptacle for catching and disposing of the maggots. 
Very little additional time or labor would be required in operating 
it. The sprinkling of the manure would be a very small part of the 
daily routine of removing the manure from the stables. Proper 
arrangements for the disposal of the maggots would require only a 
few minutes' attention at long intervals. 
Incidentally it may be noted that the maggot trap offers a conven- 
ient and easy means to the investigator or teacher who wishes to 
collect coprophagous larvae in large numbers. In the experiments 
just reported the larvae of Musca domestica L. were the most numer- 
ous, but in addition there were also collected larvae of Stomoxys 
calcitrans L., of Homalomyia, of certain Sarcophagidse, and doubtless 
of others. The total numbers collected were so large that no attempt 
was made to determine the relative abundance of the various forms. 
SUMMARY. 
Observations and experiments show that the migratory habit is 
deeply ingrained and highly characteristic of housefly larvae. 
The migratory habit appears in the prepupal stage in response to 
various internal and external stimuli. 
Of the external stimuli, moisture is perhaps the most important in 
determining the direction of their travels and the choice of a place for 
pupation. 
The migratory habit is an adaptation of great advantage in that it 
insures to the issuing adult the easiest and quickest escape. 
This deep-seated habit offers an important point of attack in the 
attempts to control the pest. 
Experiments with maggot traps show that 98 or 99 per cent of the 
total number of larvse can be made to leave the manure, provided it 
is kept moist. Even from comparatively dry manure as many as 70 
per cent can be destroyed. 
