42 



From the descriptions which I have given above of these three 

 moths, there need be no danger of confounding them. 



By comparing the moth from which I obtained the first laying of 

 eggs with the simplex moth which I captured, and the Y variety of 

 the jjrecationis moth determined for me by Prof. Grote, I find that 

 it IS readily referable to the first named species. The Celery Worm, 

 Cabbage Plnsia and Thistle Plusia are the only larvae belonging to 

 the genus Plusia that I have ever bred or seen a description of. As 

 stated above, the Celery Worm differs from the Cabbage Plusia only 

 by the black rings around its breathing pores ; and both of these 

 worms differ from the Thistle Plusia by lacking the black stripes 

 on each side of the head. 



On the 23d of April I found a Thistle Plusia which spun its 

 cocoon the next day, and was changed to a moth on the 20th of 

 May; another spun its cocoon on the 26th of June and produced 

 the moth on the 9th of July. 



On the ISth of May I obtained a laying of eggs from a Celery 

 Worm moth ; these eggs hatched out on the 24th, and one of the 

 worms spun its cocoon on the 16th of June and was changed to a 

 moth on the 28th of the same month. On the 6th of July I ob- 

 tained another laying of eggs ; these hatched out on the 10th, and 

 the last worm died August 12th, nearly full grown. I have found 

 other specimens of Celery Worms as follows : One June 21st about 

 two-thirds grown ; one nearly full grown July 2, and another 

 August 2, also nearly full grown. Those received from the German- 

 town Telegraph November 21 were about one-half grown. 



From the above dates it would appear that there are three broods 

 of Celery Worms produced in one season. The first broods issue 

 from the eggs in the latter part of May, and attain their full size 

 in the latter part of June or early in July. The second brood 

 appear from the first half of July to about the middle of September. 

 The third brood issue from the eggs in the fore part of October, 

 and becomes about one-half grown by the time that winter sets in, 

 when they hibernate and finish their growth in the following spring, 

 attaining their full size in the latter part of April. And thus the 

 cycle is completed, giving us three broods in each season, and 

 showing that these insects hibernate as half-grown worms, or larvae. 



This, at least, is the history of these insects in this locality, 

 although it is very probable that one or more additional broods are 

 produced in one season in more southern latitudes. 



The eggs of the Celery Worm moth are of a milky-white color, 

 flattened, globular, or turnip- shaped, sometimes with an impressed 

 spot in the center of the upper side ; the upper half of the egg is 

 grooved vertically; the grooves are narrow, and the spaces between 

 them are roughened. The transverse diameter is about one-sixtieth, 

 of an inch. 



