304 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 4 



tures, as may be seen from the table. It was thought that the purple 

 scale young being much larger than the red would travel faster. 

 The young purple scale has very short legs in relation to the size of the 

 body, these scarcely showing beyond the margins and this probably 

 accounts for its slow and rather awkward movements. The black scale, 

 on the other hand, is a much better traveler but, contrary to what 

 was expected, the partly grown scale when it loosened its -hold after 

 becoming fixed, could not cover the distance traveled by those just 

 emerged from beneath the parent. 



In these experiments httle difficulty was met with in keeping the 

 insects within the limits of a sheet of paper. They would almost 

 invariably travel toward the light, so that when one margin of the 

 sheet was reached it was turned around so that the opposite margin 

 was nearest the light and the scales would soon turn about and go 

 in the opposite direction. From these observations and experiments 

 where the light was regulated it is concluded that these young scale 

 insects are positively phototropic. 



Travel Over Sand and Orchard Soil 



In the experiments on the rate of travel over sand and ordinary 

 orchard soil, the material was placed in saucers, plates and large 

 sheets of black paper. A narrow strip of tree tangle-foot was placed 

 around the plate or paper a little beyond the soil to capture the 

 insects as they crossed over. Galvanized iron cylinders were also 

 sunk in the soil in the field and a strip of tanglefoot placed on this a 

 few inches above the surface. These cylinders were about 10 inches 

 high and varied in diameter from 1 to 4 feet. These were later dis- 

 carded for large sheets on which the soil was placed, or circles of 

 paper with the inside margins covered, thus leaving a strip around 

 the outer margins of the soil area where the scales could be more 

 closely examined upon making their way from the center. In the 

 following experiments the details were largely carried out by E. W. 

 Rust. 



Black Scale. — Temperature 85° F. About 50 active young just 

 taken from under the adult were liberated in a plot of sand 6 inches 

 in diameter. After one-half hour 5 had reached the outer margin 

 and in three-fourths of an hour about half of the insects had reached 

 the paper. Distance 3 inches. 



Temperature 84"^. Several hundred active young were placed in 

 the center of sand in a dish at 3.30 p. m. At 3.55 one reached the edge 

 of the dish; at 4 another; at 4.02 two more; while five more reached 

 the edge by 4.20 and ten more by 4.30. By 5 dozens had reached 



