300 Report of the Department of Extomology of the 



from 1 to 48 hours. Those that were born free remained motion- 

 less near the anal jilate of the mother for from one-half hour to 

 four hours. 



Distance the lar^vos migrate. — During the active period the larvse 

 move about very freely. The distance they can migrate unaided 

 naturally varies with the character of the, surface over which they 

 travel and with the temperature. It is not probable that they 

 travel very far over loose earth, but to determine this point more 

 obsei-vations are needed. During our investigations the nearest 

 approach to data on this phase of the subject was in the case of 

 an infested apple placed on the ground about four inches from the 

 base of a small apple tree growing in the shade in the insectary. 

 The soil about the tree was well packed and moderately moist. 

 The apple remained for three weeks during which time the larvae 

 were numerous and active, but none were found on the tree. It 

 ist possible that the larvae did not attempt to leave the fruit, but 

 a large number of cases were observed in the laboratory where 

 they wandered freely from infested apples kept under similar con- 

 ditions, thus indicating that they have a definite tendency to 

 migrate from the fruit. 



A more definite illustration of the power of the larvae to 

 migrate was furnished by a simple experiment with a single larva, 

 December 27 a young larva measuring 0.2 mm. in length was 

 placed on a smooth piece of paper at 10.05 a. m. The tempera- 

 ture of the room averaged about 74° F. The larva traveled 

 almost continuously, with occasional stops, for six hours, during 

 which time it had covered 10^ feet, or about 16,000 times its own 

 length. 



The larvae appear to have a tendency to seek sheltered places 

 on the bark and fruit before settling down. This is especially 

 noticeable in cases of moderate infestation. On fruit, the blossom 

 end or stem end is usually sought by a majority of the larva?, the 

 former often being preferred. It is possible that the position of 

 the fruit may have some influence, as, after the fruit turns down, 

 the blossom end is less often, if at all, in the direct rays of sun- 



