Severin and Severin—Habits of the Saw-fly . 
69 
LIST OF HOSTS ATTACKED IN THE EGG STAGE BY TRICHOGRAMMA 
PRETIOSA RILEY. 
Hymenoptera . 
Pachynematus palliventris Cresson. (record ?) 
Pteronus ribesii Scopoli. 
Lepidoptera. 
Alabama argiilacea Hubner. 
Autographa brassicae Riley. 
Carpocapsa pomonella (Linnaeus). 
Heliothis obsoleta Fabricius. 
lanassa lignicolor Walker. 
Laphygma frugiperda Smith and Abbot. 
Mamestra picta Harris. 
Phlegethontias sexta Johanssen. 
Platynota rostrana Walker. 
Polychrosis viteana Clemens. 
The total number of eggs deposited on one hundred leaves 
of the peach-leaved willow was three hundred and ninety-five, 
of which only five eggs were parasitized by Trichogramma 
pretiosa, whereas upon the long-leaved willow there were two 
hundred and eighty eggs deposited, and of these, six were par¬ 
asitized by this same Hymenopteron. The percentage of eggs 
which failed to hatch on account of this egg-parasite was there¬ 
fore less then two per cent. 
Besides the eleven parasitized eggs, there were sixty eggs 
which failed to hatch, out of the six hundred and seventy-five 
eggs examined. A few observations which we made may ex¬ 
plain the destruction of some of these eggs. A number of fe¬ 
males were allowed to deposit eggs on a peach-leaved willow 
and their development was observed from day to day. During 
the eight days of their development there were heavy rains, 
and, for some reason or other, a few days before hatching the 
epidermis of the receptacle of many of the eggs had been brok¬ 
en and curled up, oftentimes exposing the eggs. Heavy rains 
and strong winds prevailed during the night of the seventh and 
morning of the eighth day. A visit during the eighth morning 
