NEW YORK EXPERIMENT STATION BULLETINS 375 



weeping willow, laurel leaved willow, Kilniai-nock willow. siiina<li and 

 grape. A lint ])ul)li.sli('d in .Inly, JS!t7, by I'rof. F. ^I. Webster* includes 

 black Avalnul, Cai'olina poj^lar, loiubardy ])oplar, j^olden leaf poplar, 

 European willow, cut leaf birch, ilowerin<>- peach, llowering cherry, Amer- 

 ican linden, European linden, hard\' cataljia and mountain ash in addi- 

 tion to those <;;iven above. 



From the above lists it will be seen that the scale may be found on 

 l)ractically all classes of nursery stock grown in the east. It is not 

 known to attack citrus fruits. 



Descri])tions and life liistory. — A good idea of the general appearance 

 of the scale is given in IMate III, ligs. 1 to 4. Here the scales are shown 

 natural size and enlarged on both twigs and fruit. The female scales 

 are greatly in excess of the males, wliich is the case with most other 

 scale insects. The following description is taken from T>ul. 3 (new series). 

 U. S. Department of Agriculture Division of Entomology, by Howard and 

 Marlatt, p. 4G: "The scale of the female is circular, very slightly raised 

 centrally, and varies in diameter from 1 to 2 mm., averaging about 1.4 

 mm. The exuvite is central or nearly so. The large well-developed 

 scales are gray, excepting the central part covering the exuvia?, which 

 varies from 7^>ale to reddish yellow, although in some cases dark colored. 

 The scale is usually smooth exteriorly or sometimes slightly annulated, 

 and the limits of the larval scale are alw^ays plainly marked. The 

 natural color of the scale is frequently obscured by the jjresence of the 

 sooty fungus [Fnniago salicina]. 



The microscopic characteristics of the mature female are shown in 

 Plate II, Fig. 2. At h the ornamentation of the anal plate is shown. 

 This is of especial value in determining the species. Those who wish to 

 make microscopical examination of the insect to determine the species, 

 will find that the characteristics of the anal plate can be brought out by 

 boiling the insect for a few minutes in a weak solution of caustic potash, 

 then washing, then, after placing in alcohol for a short time, cleansing in 

 oil of cloves or other convenient cleaning solution. The specimen should 

 then be mounted in balsam. The male scale is darker than the female 

 scale, "oblong oval" in shape, "nearly tAvice as long as wide and about 

 half the diameter of the female scale." (Howard and Marlatt). The ma- 

 ture male is a delicate two-winged insect, orange yellow in color, except- 

 ing the head, which is somewhat darker. 



The main points of the insect's life history may be briefly stated as 

 follows: — In this climate, if an infested tree is examined during the 

 winter the scales will be found varying in size from less than half grown 

 to fully matured. On badly infested trees they are crowded in great 

 numbers very close together. On trees not badly infested the^y will be 

 found in groups of from two to three to many more, with numerous indi- 

 viduals scattered about on the bark. The writer has not had an oppor- 

 tunity of studying the life history of the scale in western New York 

 until within the past few weeks, and hence no observations have been 

 made as to the time the females first begin producing young in the 

 spring. On long island, however, the males mature in April and during 

 the following month the females begin giving birth to young. Unlike 

 most scale insects, the young are brought forth, in nearly all cases, alive. 

 According to Howard and Marlatt the average number of young pro- 



iOhio Agl. Exp. Sta. Bui. 81, p. 184. 



