38 BULLETIN 1032, U. S, DEPARTMENT OF AGEICULTURE. 



The phenology of the cranberry in that locality is quite vari- 

 able. Usually on the earliest varieties, such as the McFarlin and 

 Early Black, buds begin to break and the ncAv growth begins to 

 push forth about the beginning of April. The new upright growtli 

 is about three-fourths of an inch long by the middle of April, the 

 blossoms are in the " hook stage " in about a month more, and full 

 bloom comes about the beginning of June. The late varieties, such as 

 the Howe, are more variable, but the new growth starts the beginning 

 of May and attains three-fourths of an inch in about a week. The 

 majority of the blossoms are in the " hook stage '' about the middle of 

 June and fully opened by the latter part of June or early July. 



Almost none of the bogs on the Pacific coast are ever completely 

 covered with water, and the seasonal temperature is comparatively 

 equable. These conditions, coupled with the small number of para- 

 sites, enable this pest to be very destructive, the larvse feeding on 

 the buds, foliage, blossoms, and fruit throughout the growing season. 



The insect passes the winter in the egg stage. The eggs are quite 

 small, smooth, and slightly oval, with the center slightly raised or 

 rounded. They are lemon and orange yellow and are deposited singly 

 or in small irregular groups on the undersides of the cranberry leaves. 

 The young larva on hatching leaves the egg through a rent near the~ 

 edge of the upper side and then feeds for a few days on the leaf or 

 leaves near by. Later it proceeds to the tip of the upright, there 

 feeding on the unfolding buds and blossoms. 



By rearing the insect from the egg stage in an outdoor shelter 

 where conditions were maintained which approached those natu- 

 rally found on the cranberry bog, it was found that there are annually 

 two full generations and sometimes a partial third. Temperature, 

 depth of vines, and drainage are the three most important factors 

 in the hatching and development of the fireworm. 



The mature larva is very active, is about one-fourth of an inch 

 long, dark greenish yellow, with a coat of dark olive-green above, 

 and with head and thoracic shield varying from light brown to 

 black. The ravages of the larvae result in a burnt appearance of the 

 vines, as if a fire had swept over the bog. Hence the common name 

 " blackhead fireworm." 



Nearly all the larvae change to pupse in loosely constructed cocoons 

 in old leaves and trash beneath the vines. The pupa is a little less 

 than one- fourth of an inch long and of a brownish amber color. 



The adult or moth moves in quick, jerky flights, is about the same 

 length as the mature larva, and has characteristic markings of a single 

 row of short, alternating brownish and silver-gray bars running 

 diagonally to the front margin of the first pair of wings. The males 

 have an irregular dark area near the front margin on the underside 

 of the second or lower pair of wings. 



