38 BULLETIN 1032, U. S. DEPARTMENT OF AGRICULTURE. 
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 new growth begins to 
push forth about the beginning of April. The new upright growth 
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 larvae 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 pupae 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 male> 
have an irregular dark area near the front margin on the underside 
of the second or lower pair of wings. 
