THE TERRAPIN SCALE. 87 



dies. The female after mating starts a rapid growth, during which the 

 mating colors and the larval characters are lost and during which vast 

 quantities of honeydew are deposited. By the end of the twentieth 

 day upon the twig the female has assumed all the adult characters. 

 After this, growth gradually slackens until the cold of the approaching 

 winter forces the scale into hibernation. In the spring growth is 

 resumed. Maturity is reached early in June and the scale dies early 

 in July, after having lived about 13 months. 



The male, which makes the second molt and passes all of its remain- 

 ing instars, except the last day of the imago, under the protection of 

 the puparium, loses its mouth-parts at this time and lives during the 

 remainder of its life upon nourishment taken in the first two instars. 

 The third or prepupal instar lasts about 2 days and is a period of rapid 

 metamorphosis, in which the larval organs are replaced by the adult 

 structures. In the fourth or pupal instar, which lasts for about 8 

 days, the adult organs reach their full development. At the fourth 

 and final molt the imago escapes from the pupal case, but remains for 

 about 2 days under the puparium before emerging, when it migrates 

 at once to the twigs, copulates, and then dies, after having lived about 

 49 days. , 



SUMMARY OF REMEDIAL MEASURES. 



An endeavor was made to prevent the soot injury which is the main 

 cause of complaint from orchardists against this scale. During the 

 first season one series of sprayings was made to control it in the 

 presence of the living scale, and another series was made to control it 

 by destroying the scale. It was found impracticable to control the 

 ' ' soot " directly. Accordingly in the second season all sprayings were 

 made against the scale. Seven groups of materials were tested, the 

 first of which contained corn oil, rosin oil, and gasoline. Of these, the 

 two former were good treatments, but were very injurious to the 

 trees. The latter was inefficient but gave promise as a wax solvent 

 and penetrant. 



Miscible Oils. 



The second group contained miscible oils. Nine experiments were 

 made with miscible oil, including 5 with miscible oil and gasoline, 

 and 2 with miscible oil and nicotine. 



In the first case it was evident that miscible oil was injurious when 

 used in the winter at effective strengths, but that it could be used 

 without injury if applied in the spring between the swelling and the 

 bursting of the fruit buds. It was also evident that healthy 1 1-year- 

 old trees could be sprayed for three consecutive seasons with miscible 

 oil 1 to 18 without injury to the trees, and that the scale could be 

 controlled by two seasons' spraying with this oil. 



