52 MASS. EXPERIMENT STATION BULLETIN 2:39 



The worms reiiuiin sheltered at nijiht and feed in tlie daytime in tiieir first 

 stages, usually being most active from 9 to 11 a. .-m. and from 3 to 5 i-. .-m. 

 Their habits change as they grow and they feed mostly at night, remaining 

 inactive and more or less concealed during the day unless they are starved. 



The Pupa. 



Pupation usually liecomes general toward mid-. July on the Cape, but some 

 caterpillars remain till August. When the worms abound they connuonly 

 collect in masses to pupate. The male pupae are from three-fifths to four- 

 fifths of an inch long and the female from three-fifths of an inch to one and 

 two-fifths inches. They are deep brown and bear consideral)le yellow hair 

 (Plate Four, fig. 9). They usually are found on the sand on cranberry bogs, 

 often covered with litter, Init tb.ey also oi'cur u)) among tlie vines. The ])ui)ai 

 stage lasts 7 to 17 days. 



The Moih. 



The .sexes are very unlike. The nude (Plate Four, fig. 10) expands about 

 an inch and a half. Its antennae are bushy and with the up})er side of the 

 body and wings are dingy brown, the fore wings having irregular dark brown 

 markings. The head and under side of the body are yellowish white. All the 

 wings are light brown underneath. 



The female (Plate Four, fig. 11) expands about two inches. Its antennae 

 are dark brown and much less bushy than the male's. The hind end of the 

 abdomen is dingy reddish brown. The rest of the body and the wings are 

 nearly white. The fore wings are marked irregularly with difl'erent shades of 

 brown and all the wings have dark brown spots at regular intervals along 

 their outer margins. 



The motiis emerge in late July and August. The males are slender-bodied 

 and fly actively l>y day with a peculiar zigzag flight, but the females are heavy- 

 bodied and sluggish and cannot fly. 



//oic Bo(is liecome Infested. 



Bogs get infested in the four following ways: 



1. Ihi the Hatching of Eggs laid on the Bog the Year Before. — This is a 

 conunon cause of trouble on bogs that have been neglected, e.specially dry 

 bogs. These infestations usually defoliate rounded areas. 



2. Jh/ ]\'iiid Drift of the Worms in their First Stage. — This is the main 

 cause of infestation. The uplands around cranberry bogs, often from ten to 

 fifty feet high and usually wooded, furnish ideal conditions for wind disper- 

 sion. Infestations from wind drift often are thickest near the bog margin 

 and diminish toward the center. They seldom, if ever, develop in round 

 patches. 



Often there is a high mortality anuing the wind-borne larvae after they 

 reach a cranberry bog. It seems to be greatest in their first stage and prob- 

 ably is due mainly to reduced vitality, this making them readily subject to 

 disease and other killing agents. The nature of cranberry foliage as a food 

 may be a factor. 



