18 



more or less unnatural conditions, but similar to what are experienced 

 in greenhouses in every month throughout the year. 



LIST OF FOOD PLANTS. 



The known host plants of this species may be summarized as fol- 

 lows: Celery, cabbage, beets, and tobacco, among crop plants; and of 

 greenhouse and other ornamental plants, Ageratum, geranium, ground 

 ivy (Nepeta glechoma), German and Kenil worth ivy, violet, heliotrope, 

 wall flower, wandering Jew ( Trades cantia zebrina), dahlia, daisy, Jus- 

 ticea, chrysanthemum, carnation, Cineraria, begonia, abutilon, roses, 

 pelargonium, anemone, nasturtium, moonvine, Swainsonia, Genista, 

 Plumbago, Matricaria, Passiflora, Ruellia, T} T daea, Lobelia, Veronica, 

 Lantana, Deutzia, nodding thistle (Carduus), and ornamental Ambrosia. 

 Of weeds it has been observed on hedge mustard (Sisymbrium offici- 

 nale) and ragweed (Ambrosia). 



SUMMARY OF THE LIFE HISTORY. 



The life history of the insect is now practically known, and the 

 summary which follows is fairly complete. This species occurs out 

 of doors, where it sometimes does considerable damage to celery, but 

 aside from this its injuries are confined, for the most part, to plants 

 in conservatories. 



The moth lays its scale-like white eggs on the plant which is to serve 

 as the food for its larvae. The eggs hatch in from five days to about 

 three weeks, according to temperature. 



The larva, soon after it is hatched, usually conceals itself or begins 

 the process of doing so by drawing together, by means of its white 

 silken web, a portion of a leaf, or it thus joins two contiguous leaves 

 and feeds upon their lower surface. The work of the larvae has been 

 most noticeable in secluded situations, and, on most plants, upon the 

 terminal leaves, which they eat full of holes. The}^ work chiefly 

 at night, and by day rest in the same location; here also they transform 

 to pupae or chrysalides, and subsequently to the imago or moth state. 

 Occasionally, at least, perhaps in the case of the hibernating genera- 

 tion out of doors, the larvae seek more protected locations for their 

 transformations. 



Hibernation either begins in the larval state and ends toward the 

 approach of warm spring weather with the pupa, or is passed in the 

 pupal condition. In warm indoor temperatures there is no definite 

 hibernating period. 



The larval period varies also, according to the temperature at the 

 time of tran formation, from an observed minimum of about three 

 weeks to perhaps five weeks, and the pupal period from one to probably 

 two weeks. 



