THE CHICKEN MITE. 7 



Seventh engorgement and deposition: 



During the night of September 17 12 females were placed with a host and 10 

 recovered. Seven of these deposited, one of the other three died, and one died 

 soon after deposition. 



Eighth engorgement and deposition: 



The eighth engorgement was made during the night of September 22. All 

 of the eight females applied to the host were engorged. Six of these deposited, 

 beginning September 23 and finishing September 26. One female died without 

 depositing and one failed to deposit. 



On September 28, 100 per cent of the eggs deposited following the eighth 

 engorgement had reached the nymphal stage, thus showing that fertility per- 

 sisted though males were not with them since prior to the first feeding. 



Ninth engorgement: 



On September 2S the seven remaining females were put on a host for the 

 ninth engorgement, but as only one was recovered the following morning the 

 experiment was discontinued. 



A summary of the depositions, with the number of eggs deposited 

 by each female, is given in Table I. 



Table I. — -Summary of oviposition records of Dermanyssus gallinae, Dallas, Tex., 



1916. 



Depositions. 



Number of females depositing to 8 

 eggs each. 



Total 

 number 

 of eggs. 



Average 



per 

 female. 



Number 

 of females 

 depos- 

 iting. 



Number 

 of females 









1 



2 



3 



4 



5 



6 



7 



8 



engorged. 



First* 

































 1 

 2 

 2 

 3 

 3 

 2 



6 

 2 

 

 

 1 

 

 



4 

 1 

 2 

 

 

 4 

 1 



11 



2 

 3 



4' 

 5 

 1 

 1 



14 

 11 



10 

 5 

 2 

 

 2 



11 

 14 



6 

 5 

 1 

 1 

 1 



4 

 11 

 9 

 5 

 2 

 1 

 



3 



7 

 1 

 1 

 1 

 

 1 





 

 2 

 

 

 

 



203 

 239 

 160 

 94 

 48 

 22 

 25 



3.8 



4.98 



4.84 



4.7 



4.0 



3.14 



4.16 



53 

 48 

 33 

 20 

 12 

 7 

 6 



53 



Third 



49 



Fourth 



35 



Fifth 



22 



Sixth 



15 





10 



Eighth 



8 







1 Not recorded. 

 DISCUSSION OF RESULTS OF LIFE-CYCLE EXPERIMENTS. 



No attempt was made in the experiment to see how quickly the 

 life cycle could be accomplished. In the foregoing experiment the 

 actual time taken for the mite to pass through its life stages was 

 10 days. Under natural conditions in August without doubt this 

 time would be reduced to at least &§ days. Tables II and III show 

 in brief the actual time taken in the experiment and the probable 

 time in nature. 



