8 



It was first recorded as a tobacco pest on the mainland in 1897 by Mr. 

 Gerald McCarthy/' 



The small size of the larva will render its presence difficult of detec 

 tion. at least in the early stages of development. The occurrence of 

 the splitworm in the tobacco field will probably be first noticed by the 

 symptoms of its work. This insect receives its common name because 

 of its habit of mining between the upper and lower surfaces of the 

 leaf, causing not only a blotch visible from either side, but frequently 

 a deformity as well. The portions of the leaves thus affected become 

 at first lighter in color and finally dry and parchment-like. While 

 the parts of the leaves remain intact, their value is greatly lessened, 

 especially for wrapper purp ses. 



The eggs are deposited on the leaves and the young minute larva?, 

 on hatching, gnaw at once to the tissues between the epidermal layers. 



On reaching maturity the 

 larvae drop to the ground 

 and, after first spinning a 

 slight silken cocoon, pupate 

 beneath the loose soil or 

 among the rubbish found 

 at the surface. Mr. War- 

 ren T. Clark h sums up the 

 life cycle of this insect as 

 follows: 



To complete the cycle ordina- 

 rily, 63 to 69 days are needed, 

 save for the winter generation, 

 when this time may be extended 

 to 84 or 85 days; this, of course, 

 under the temperature condi- 

 tions of Berkeley. This time is divided thus: Egg state, 7 to 10 days: larva?. 42 to 45 

 days ordinarily, winter generation, 9 weeks; chrysalis, 14 to 16 days: adult life, 

 indefinite, but short. 



In the equable climate of these islands the life cycle is undoubtedly 

 shorter than this, and at least two generations are possible during the 

 growth of one crop. 



REMEDIES. 



Under this heading Mr. McCarthy says: 



Clean cultivation of the growing crop, with frequent stirring of the soil close up to 

 the plants, will destroy the dormant pup?e or cover them so deep that the moth will 

 be unable to find its way to the surface of the ground. A close watch should be 

 kept, and when blotch mines are seen on leaves the inclosed caterpillar may be 

 easily crushed between the thumb and finger. The leaves will then soon repair the 

 damage. 



« A New Tobacco Pest. North Carolina Experiment Station Bui. 141, 1897. 



6 The Potato Worm in California. California Experiment Station Bui. 135, 1901. 



