6 BULLETIN 1032, U. S. DEPARTMENT OF AGRICULTURE. 



to that of the blackhead fireworm. nor has the cranberry there any 

 other pest which annually destroys so much as this one. 



The young larvse start to feed on the newly growing tips shortly 

 after the}^ hatch, in the months of April and May, and continue 

 their work throughout the growing season, attacking in greater or 

 less severity the buds, blossoms, and later the berries, injuring 

 the berries by boring into them and causing them to shrivel and 

 dry and often to fall from the vines. The most noticeable feature 

 of the attack of the fireworm during the middle or latter part of 

 the summer is the burnt appearance of the vines which results from 

 the work of this insect, suggesting the name fireworm. Since the 

 terminals are most affected, few if any fruit buds are set when the 

 vines are badly infested, and as a result nearl}^ all the crops of the 

 current season and of the following year are destroyed by the 

 feeding of the larvae during a single season. The vines, while never 

 completely killed, are very much stunted and by the end of the 

 summer are left stripped of the majority of the leaves. They are 

 often brittle, and in the case of long-standing infestation are short 

 and scrubby with numerous short and crooked branches as a result 

 of being prevented from making a natural terminal growth. From 

 this condition they do not usually return to their normal produc- 

 tiveness until good control work has been in force for several years. 



NUMBER OF GENERATIONS. 



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

 shelter it was found that it passes through two generations and 

 sometimes a partial third. For example, the hatching of the winter 

 t^ggs starts the first generation, and the resulting larvse which change 

 into pupae and moths also belong to the first generation. 



The eggs that these moths lay start the second generation. Con- 

 trary to the behaA^or of this pest in the East, only about four-fifths 

 of these eggs hatched to form a second generation the same season in 

 Avhich they were deposited. The remaining one-fifth did not hatch 

 until the following spring. 



All the eggs deposited by the moths resulting from the second set 

 of individuals are known as the eggs of the third generation. So 

 far as is known, in eastern cranberry regions the eggs of this genera- 

 tion do not hatch until the following spring. On the Pacific coast, 

 however, it was found that about one-third of the eggs of this gen- 

 eration hatched late in the summer, forming a third generation of 

 larvse. Because of adverse weather conditions toward the latter 

 part of the season, none of these larvse developed into pupse and 

 moths. This generation is therefore called a partial or incomplete 

 fifenei'ation. 



