22 MASS. EXPERIMENT STATION BULLETIN 189. 



main stalk or flower stem, but the favorite point is at the junction of 

 flower stems with the main stalk. The tunneling larva soon consumes 

 the interior of the infested stalk or stem, and that portion first wilts and 

 then breaks over in a djdng condition. It is then very conspicuous in 

 contrast to the stems not infested, and ruins the appearance of dahlia 

 plantings. Half a dozen or more larvse have been cut from a single dahha 

 flower stem. 



The principal point to be considered in connection with the infestation 

 of dahha plants by larvae of the borer is that the species may possibly 

 be disseminated through the medium of cut flowers. 



Chrysanthemwn and Gladiolus. 



The stalks of chrysanthemums and gladioh are tunneled by larvse of 

 the European corn borer in a similar manner and with the same results 

 as has been described for dahlias. Infested chrysanthemum stalks are 

 commonly found in out-of-door gardens during the late summer and 

 fall, and also in greenhouse plots. This characteristic renders chrysan- 

 themums economically important because of the possibility that the 

 pest may be accidentally spread by transporting recently infested plants 

 which have not yet shown external effects of the larval injury. 



Infested gladiolus stalks are found in out-of-door gardens during the 

 late summer, and though not as important economically as chrj^santhe- 

 mums, this plant may also be a source of danger through the accidental 

 transportation of infested plants to areas not yet inhabited by the pest. 



Timothy and Foxtail. 

 Small larvffi of the European corn borer have frequently been found 

 feeding upon the seed heads of timothy and foxtail. This damage is not 

 important economically, except that it affords a host for the larvse of the 

 pest until they have reached a stage in their growth when they are large 

 enough to attack other food plants. Larvse of the species have never 

 been observed to feed within the stalks of these plants, and the plants 

 are never noticeably injured. 



Miscellaneoios Plants. 

 The stalks of lady's-thumb, burdock, horseweed, beggar-ticks, purslane, 

 crabgrass, mare's-tail, panicgrass, goldenrod, thistle and apple of Peru 

 are often entered and tunneled by partly grown larvae of the European 

 corn borer. These plants are rather numerous in restricted areas through 

 the infested region, and serve as intermediate hosts of the borer, although 

 the plants themselves are of no economic importance. 



Celery. 

 Nearly full-grown larvae of the borer have been observed to enter and 

 tunnel the outside stems of celery plants. This injury, however, has 



