182 BULLETIX 190. 



piece wliicli it tlien folds over. In either case the inside of tlie 

 folded portion is thoroughly lined with silk. In this cocoon, the 

 caterpillar transforms in a day or two into the third stage of the 

 insect's life — the pupa or quiescent stage, shown much enlarged 

 at J? in figure 49. The pupa is not quite half an inch long (9 to 10 

 mm.) and is dark brown in color, lighter on. the venter." The 

 pu])al stage lasted from twelve to seventeen days. The emergence 

 of the moth (figure -18) then completed the life-cycle of the insect 

 as observed in the greenhouses here. 



As the life-cycle may be passed througli in from forty-four to 

 fifty days, and as the insect breeds freely during the whole year in 

 greenhouses, seven or eight generations may occur indoors. Forbes' 

 observations (Bull. 60, 111. Exp. Sta., p. 451:) indicate at least four 

 generations annually outdoors. He also states that his observations 

 indicate the hibernation of the insect in the imago or niotii stage 

 outdoors in IlUnois. 



With so many broods in a year, this insect is capable of doing 

 much damage even to outdoor crops. AVhen once thoroughly 

 established in a greenhouse it will ruin thousands of soft-leaved 

 plants unless it is persistently watched and fought. 



Remedial measures. — The insect may be readily transported on 

 plants unnoticed in its egg or young caterpillar stages, and it is 

 thought to have been introduced into our horticultural greenhouses 

 on chrysanthemums from an infested locality. Hence one should 

 carefully scrutinize all soft-leaved plants received from other green- 

 houses ; the eggs will usually escape notice, but the work of the 

 caterpillars will soon reveal their whereabouts. Any such plants 

 found infested should be quarantined somewhere until the pest is 

 annihilated. But there is no practicable way of preventing the 

 moths from flying into greenhouses in summer from infested outdoor 

 plants, and the liability of infestation may be as great from this 

 source as from the other. 



* tSLilT hairs project from the dorsum of the thorax, as shown at ]) in figure 49, 

 and from a slight tubercle on each side the dorsum of the abdominal segments a 

 less stiff hair projects, curves backward and mesad, often meeting the hair from 

 the opposite side (see p in figure 49). Eight curved bristles project close together 

 from the tip of the caudal segment and their curved ends meet and are caught 

 into the silk lining of the cocoon. Four thoracic spiracles show very distinctly. 



