658 EXPERIMENT STATION EECOED. 



effects on the growth of the trees. While it can not be considered as a 'perfect; 

 remedy for ridding trees of scale yet it is the best preventative that may bei 

 employed. At the same time its power to kill all scale is not constant. It' 

 appears that whale-oil soap as a fall dip is promising, but more extensive tests 

 with various types and strengths must be made before definite conclusion can 

 be reached. . . . The results herein recorded have justified further tests of 

 lime-sulphur and whale-oil soap, and experiments with these will be conducted 

 in the fall of 1910." 



The terrapin scale, T. B. Symons and E. N. Cory {Maryland Sta. Bui. lJf9,' 

 pp. 83-92, pi. 1). — This bulletin includes a report of biological studies and con- 

 ti'ol experiments conducted during 1909-10. 



While the terrapin scale was luiown to occur in Maryland in 1898, it was not 

 recognized as of economic importance until 1906, in the fall of which year it was 

 reported from Frederick and Washington counties, its injury in 1 or 2 orchards 

 being quite severe. During the past 2 years it has spread rapidly, so far as 

 known the most serious outbreaks having occurred in Kent, Washington, and 

 Anne Arundel counties. The loss to orchardists is not so much from injury to 

 the trees as to the fruits, due to a black fungus which develops in the honey- 

 dew, rendering the fruit unsalable at remunerative prices. 



The scale locates on the outer limbs and branches causing them to become 

 stunted and the leaves to drop off. In observations made during 1910, the first 

 larvte appeared June 4, eggs continuing to hatch for as long as 6 weeks. " The 

 larvfe immediately crawled to the leaves and settled along the midrib and veins, 

 usually on the underside. Here, the larvte become considerably longer than 

 broad, are translucent, appearing as greenish white spots. Development con- 

 tinues on the leaves, the scales remaining here for about 6 or 8 weeks, the males 

 reaching maturity. They fertilize the females which then return and settle 

 permanently on the underside of the smaller twigs and branches. The first 

 record of their return to the twigs is August 13. Here, the females continue to 

 develop through late summer and early fall, wintering as partially mature 

 insects." 



" So far as observed the terrapin scale infests peach, plum, maple, and apple. 

 Peach seems to be its favorite food plant in this State, although we have found 

 plum trees badly infested. Infested twigs of i"ed maple were sent in from 

 Frederick County and the scales vrere observed on apple twigs taken from a 

 tree that stood in the midst of a badly infested peach orchard." CoccopJiagus 

 lecanii, the parasite most abundant in 1910, was reared from practically every 

 lot of terrapin scale collected though seldom in large numbers, and 2 other chal- 

 cidid species, ApJtycus stoniachosus and Encyrtus sp., w^ere reared in small 

 numbers. 



While experiments conducted in 1906-7 (E. S. R., 19, p. 859) indicated that 

 both miscible oils and lime-sulphur would control the pest, it has since been 

 found that lime-sulphur has but little, if any, effect, the terrapin scale having 

 spread enormously in orchards that have been properly treated annually with 

 this mixture. In experiments conducted in the fall of 1909 and spring of 1910 

 " soluble oil at the rate of 1 : 13 proved dangerous when sprayed in the fall, 

 but proved very effective in the spring, with no damage to the buds, either in 

 double or single application. At the rate of 1 : 20, sprayed when the fruit buds 

 showed pink, no damage occurred to any trees, and the scale was controlled, 

 though not entirely eradicated. Spray-On, at the rate of 1 : 12, required a 

 double application in order to be effective. No damage to trees. Scalecide, at 

 the rate of 1 : 10, sprayed in the fall, proved effective in controlling the scale, 

 and showed no damage to the ti'ees. A double application killed the few re- 

 maining scale not hit by the fall application, but killed buds and small twigs. 



