20 MONTANA EXPERIMENT STATION BULLETIN 408 



During 1941 and 1942, however, no reports were received and nv 

 damage was seen. The moist spring of 1942 would indicate that it is 

 not likely to be a problem during the 1943 growing season. 



CORN earworm.— The heaviest infestation of sweet corn by 

 the corn earworm (Heliothis armigera (Hbn.) ) in many years was 

 experienced during the spring of 1941. Although it was general 

 throughout the State, the greatest damage was done in the Bitter- 

 root Valley where many early plantings were a complete loss. Ap- 

 pearance of adults and egg laying occurred before the silks ap- 

 peared and by the time they were well out the larvae were found 

 in the tips of the ears. The abundance of adults early, together with 

 the mild winter preceeding, indicate a possibility of overwintering 

 in this region. In 1942 there were fewer of these pests than usual 

 over much of the State and no great abundance was reported any- 

 where in Montana. Control is discussed in Montana Extension 

 Circular Series A — 11. 



raspberry ROOT OR CROWN borer. - Raspberry plants 

 which appear to be stunted and with little vigor, or on which the 

 lateral spring growth wilts suddenly causing the death of the cane, 

 should be examined for the attack of the raspberry root or crown 

 borer {Bembecia marginata Harris) . This injury is most apparent 

 in old plantings and in some parts of the country is said to be a 

 rather important pest. The only specimens in the Montana Agri- 

 cultural Experiment Station collection were taken in Bozeman in 

 August of 1938 and 1942, although reports of the occurrence of 

 borers in raspberries on the east shore of Flathead Lake have been 

 received. 



The adult of this species is a slender, wasp-like, clear winged 

 moth. It is rather sluggish, and may be found sitting on the leaves 

 of raspberries or flying about the plantings late in the summer. It 

 lays its eggs on the leaves and canes, and the larvae which hatch 

 from these eggs bore into the canes close to the crown. They feed 

 on the canes in the fall and pass the winter in this situation. In the 

 spring they work their way down into the crown where they feed 

 and pass the second winter. The larvae at this time are yellowish- 

 white, fleshy, with the body segments showing up strongly 

 because of the narrow constrictions between them. Pupation 

 occurs the following spring and the new adults appear about the 

 first of August. It thus takes two years for a generation to develop. 



Besides raspberries, loganberries and occasionally blackberries 

 are known to be attacked. Canes which are not vigorous or which 

 shown signs of rapid wilting should be removed by cutting as close 

 to the crown as possible. The application of a summer oil during 

 the first ten days in August and at two-week intervals after that 

 has been recommended to kill the eggs. 



raspberry fruitworm (Byturis unicilor Say) . — At the time 

 of raspberry picking it is not uncommon to find the core of the- 



