October, '19] 



ABBOTT: NAPHTHALENE VS. CHICKEN LICE 



401 



Table IV gives the results of tests with these nest eggs against lice 

 on setting hens. 



Table IV. The Results of Tests with Naphthalene Nest Egos Ag.unst Chicken Lice Infest- 

 ing Setting Hens 



Test No. 



Duration of 

 Test 



Results 



Number of 

 Chickens 

 Hatched 



Remarks 



7 days 

 21 ■■ 

 14 

 11 

 20 

 22 



9 

 23 

 23 



Not noted 

 Still infested 

 Not noted 

 Still infested 



do 

 Not noted 

 Still infested 



do 

 Not noted 



Hen left nest 



Hen did not remain constantly on nest 



Hen left nest 



do 

 Hen did not remain constantly on nest 

 4 hens used; three left the nest 

 Hen left the nest 

 Many mites in nest 

 6 hens used; 5 left the nest 



1 Three chickens died. 



2 Four chickens died. 



This table shows that, in every case where records could be taken, 

 the naphthalene nest egg did not reduce the number of lice, although 

 in Tests 2, 5 and 8 the hens remained more or less constantly on the 

 eggs for about three weeks. These results were confirmed by exami- 

 nations made at irregular intervals on the hens that left the nests. 



It will be noted that in six of the nine tests the hens left the nests 

 and in two other tests the hens did not set well, leaving only one hen 

 that completed the full incubation period in a normal manner, and 

 from this setting of sixteen eggs only three chickens survived. Tests 

 6 and 9 are of particular interest, since they show the effects of naph- 

 thalene nest eggs on setting hens under conditions of extremely hot 

 weather. These tests were made in a barn where the temperature 

 ran very high and the hens were all very seriously affected by the naph- 

 thalene eggs. After setting for a period ranging from one to four days, 

 eight of the hens used left the nest, showing very pronounced signs 

 of injury which in some instances lasted for several days. The symp- 

 toms were very similar to those produced Ijy dusting with naphthalene, 

 but were much more pronounced and recovery was much slower. The 

 exact cause of this injury is not known, but it may be that the naphtha- 

 lene is toxic when absorbed through the skin. That the naphthalene 

 is taken into the body was determined by one experiment where a 

 hen, that had been setting for some time on a nest egg containing 

 only 0.49 per cent of naphthalene, was killed by the writer, and when 

 cooked twentj^-four hours later was found to taste so strongly of naph- 

 thalene that it could not be eaten. 



The fact that only 18 chicks hatched from 75 eggs and tliat 7 of 

 them died within 2 or 3 days would indicate a vcr>' pronounced injury 

 from the naphthalene nest eggs, but since in almost every case the 



