INBREEDING A. BETULARIA. 41 
Inbreeding Amphidasis betularia. 
By Cart. BOWATER, R.A.M.C.T., M.C., F.E.S. 
In the course of an experiment, undertaken in 1909 in order to 
investigate the heredity of melanism in Lepidoptera, Amphidasis betu- 
laria was one of the species used, and it proved itself capable of with- 
standing considerable inbreeding if due care be taken. 
In many cases pairings were infertile, and those fertile often pro- 
duced larvee so weak that they failed to reach maturity, but several 
families were carried through each year, and the strain was kept going 
till August, 1914, and then my wife, although quite untrained in 
entomology, took over the larvye, and with some aid from my sister, 
carried them through, and cared for a further generation in 1915, 
which successfully produced imagines in 1916. The 7th generation. 
I record this now as I fail to find in the literature a record of 
success with more than three generations of this species. 
The original parents were Black x Type, their offspring all inter- 
mediate. Four pairings amongst these produced four families consist- 
ing of type and intermediate specimens. A type g from one and an 
intermediate ¢ from another were paired and produced a family (the 
only one in the year) of 89 specimens (a good example of clean Men- 
delian segregation), 19 being strictly type, and 20 intermediate, and 
all the 20 are exactly the same style. 
A type § and an intermediate @ were paired, and in 1914 five 
moths emerged, two type and three intermediate. The darkest of the 
latter, a 2, paired with a wild Bexley black g, and deposited about 
400 ova, from which 250 pupe were raised, and in 1915 107 black, 60 
intermediate and 59 type moths emerged. 
Two of the black were paired, and their family of twelve, all black, 
appeared last year. 
Seven hundred and thirty-one specimens were reared in the whole 
experiment. Apple and sallow were used as food-plants. 
ao x ae 
Inter. 
3X gx & 
dl | 
T & Inter. T & Inter. 
ri x 2 
| 
B + Inter. + T 
ox 
| 
B Marcu 15tTu, 1917. 
