1910] Reiff — Resistance of Gypsy Moth Eggs 161 
SOME EXPERIMENTS ON THE RESISTANCE OF GYPSY 
MOTH EGGS TO THE DIGESTIVE FLUIDS OF BIRDS. 
By WiuuiAm ReEIFr.t 
The subject of the present paper has already been referred to in 
a previous article published in one of the recent numbers of this 
journal. There I referred to the investigations of Alexander Bau 
who determined by numerous experiments that the eggs of certain 
species of Lepidoptera will pass out undigested, and still remain in 
a living state after a trip through the stomach and intestines of 
some species of birds. On this account I thought that Gypsy Moth 
eggs which have extremely hard chitinous shells, might readily 
withstand such a journey without damage. If this should prove 
true the sporadic diffusion of the Gypsy Moth in New England, 
which has hitherto been so mysterious, might find a_ partial 
explanation. 
In selecting the birds used for these experiments it proved im- 
possible to get native species and I was compelled to substitute 
foreign birds such as sparrows and finches. Altogether species 
belonging to the following four families were utilized: 
Fringillide. (German Canary Bird, English Yellow Hammer 
and English Chaffinch.) 
Turdide. (Japanese Robin.) 
Bubonide. (Screech Owl.) 
Columbide. (Carrier Pigeon.) 
German Canary Bird. 
One dispar egg cluster overwintered in outside temperature was 
divided into two parts early in March, 1910. One half was put 
apart for control while the other was separated into its individual 
eggs. The eggs were put into small crumbs of bread to which small 
pieces of cochineal were added for the purpose of tracing the eggs 
in the droppings of the bird. The food thus prepared was given 
to the bird early in the morning and had passed through the ali- 
mentary tract at the expiration of an hour and twenty minutes. All 

1 Contributions from the Entomological Laboratory of the Bussey Institution, 
Harvard University, No. 24. 
