LECTURE ON ENTOMOLOGY. 447 



We frequently have no less than four distinct parasites feeding on one 

 another, and all of them on a vegetable feeder. 



Mr, Galuslia — Is it invariably the case that parasites are much less in size 

 than those upon which they prey ? 



Mr. Eiley — True parasites, as distinguished from cannibals, invariably and 

 necessarily are. I have mentioned two parasites on this apple worm. I will 

 try to describe one: it is the macrocentrus delicatus. This fly punctures the 

 worm while yet in the heart of the apple, and spins its cocoon inside the 

 cocoon of the apple worm. This is a yellow fly ; the other is a black fly, 

 pimpla aniudijjes. Instead of destroying it before \i has assumed the chrysalis 

 state, it does not destroy it until after. 



Besides these, I know that two cannibal beetles — the Pennsylvania soldier 

 beetle, and th.e two-lined soldier beetle, as well as the ants and cockroaches, — 

 destroy it as it leaves the fruit. Then there is a species of trogosiia which Dr. 

 LeBaron and I have found in the bandages, destroying the worm. I mention 

 this to show that it has its enemies notwithstanding that it lives in the center 

 of the apple, and descends from the tree at night. 



With regard to liquids or lights, I will simply say they are of no practical 

 use. Both modes kill as many of the enemies of the codling moth as of the 

 codling moth itself. 



A few words as to its food plants: Tha apple is essentially its food plant, 

 but in late years I have seen it in pears, plums and peaches, and it breeds in 

 wild crabs. From these facts we see how foolish is tiie suggestion of Dr. J. S. 

 Parker, of Ithaca, New York, to exterminate the codling moth by ceasing to 

 grow apples for one or more years. It would thereby simply be forced to breed 

 in other fruits. 



Mr. Barler — At what time is the egg deposited ? 



Mr. Eiley — Just about the time the blossoms are falling and the fruit is 

 forming. 



I should have stated the difference between the first and second broods. In 

 the first brood the egg-state lasts about ten days, the larva-state about thirty 

 days, the chrysalis-state twelve to fourteen days. 



' The second brood, however, remains in the larva-state all through the winter, 

 no matter whether it leaves the fruit in August or November. This fact I first 

 recorded in this country, not knowing that the same fact had been recorded 

 by a French author in 1850. 



Another point that I have not mentioned, and among others which I have 

 not had time to mention, is the necessity for destroying these winter cocoons 

 in our cellars and storehouses. The necessity of destroying them becomes ap- 

 parent, because we keep them out of the way of the natural enemy that would 

 otherwise devour them. 



A Member — Could you find them in an apple barrel that was hooped up ? 



Mr. Riley — Yes, sir; under the hoops — great numbers of them. 



A Member — Did I understand you to say it was purely nocturnal ? 



Mr. Eiley — It might fly, to endeavor to escape, in the day, but it is essen- 

 tially a nocturnal insect. I have found the moth at rest in the day-time under 

 the bark, and I have found it in the house. Even in confinement it rests 

 during the day, and becomes active during the night. 



A Member — Are they not attracted by light ? 



Mr. Eiley — Very slightly, indeed. If you have a light in the orchard, and 

 some way to secure them, you will find a few of them among hundreds of other 

 species. 



