236 STATE BOARD OF AGRICULTURE. 



NATURAL ENEMIES. 



The parasitic hymenopterous insect Coccophagus lecanii was bred from typical speci- 

 mens of this scale;* and a single scale collected by the writer in the northern part of 

 the State was destroyed by the fungus disease, Oordyceps clavulala (Schw.) Ellis. t 

 Fig. 4, b. Fig. 4, a, shows the same fungus on a Lecanium infesting ash, collected in 

 the same county. This fungus is one that attacks Lecaniums on several hosts espec- 

 ially in moist situations. 



As has been explained, this species is very closely related to the New York plum 

 scale and this latter scale has been very carefully experimented with and methods for 

 controlling it have been found that have proven successful and satisfactory. It is 

 almost certain that the same methods will prove perfectly satisfactory when used 

 against this scale. 



REMEDIES. 



Prof. Slingerland was very successful in killing the New York plum scale with a spray 

 of kerosene emulsion applied during the winter months. He used the Riley-Hubbard 

 emulsion diluted^four times, spraying very thoroughly and hitting each scale with the 

 mixture. This mixture should not be used under any considerations when the leaves 

 are on the tree as it is likely seriously to injure the tree. The latter part of winter or 

 very early in the spring is the best time to use it, choosing if possible, a bright sun- 

 shiny day with little or no wind. 



There is a time, during the first half of July, when the young scales are moving about, 

 just after hatching, at which time a weaker spray, emulsion diluted perhaps nine times, 

 may be applied with some benefit, but the amount of work and material necessary at 

 this time is greatly in excess of that required for winter spraying. In July, the young 

 scales are spread over the leaves, and as each one must be hit to be killed, many escape. 

 During the winter months, when they gather on the branches, it is far easier to reach 

 them. 



Mr. V. H. Lowe also found this to be true as stated in his MSS. work on the N. Y. 

 plum scale. 



No doubt a treatment during the winter months with whale-oil soap applied as for the 

 San Jose scale, would prove effective, but whale-oil soap is much more expensive than 

 the emulsion, and furthermore it is liable to be injurious to the fruit buds, especially so 

 if applied early in the season. In case the infested orchard is a large one and the owner 

 has a pump known as a mixer, one that draws kerosene from one tank and water from 

 another, mixing them as they pass through the pump, it may be found expedient to use 

 this. There is an element of risk in using a mixer on stone fruits but in case of a 

 pest like the one in hand, it sometimes is thought worth while to run a little risk. In 

 no case use the mixture stronger than 20 per cent and take samples of the liquid from 

 time to time in order to measure the amount of oil after allowing it to separate out and 

 rise. This will give a check on the machine. 



Following is a list of some of the more important papers on the New York plum scale 

 and the apricot scale: 



The Apricot Scale, Lecanium armeniacum Craw. 



Craw, Alexander Cal. State Bo. Hort. 1889, p. 198. 



Cal. State Bd. Hort. 1891, p. 197. 

 Webster, F. M., Can. Ent. Vol. xxx, 1898, p. 81. 



Britton, W. E., Ann. Rep. Conn. Exp. Sta. 1898, p. 273. 



Ann. Rep. Conn. Exp. Sta. 1899, p. 242. 

 Felt, E. P., U. S. Dept. of Agr., Div. of Ent. Bui. 17 n. s. 1898, p. 22. 



• Kindly determined for me by Dr. L. O. Howard, of the Department of Agriculture, Wash- 

 ington, D. C. 

 t Cornell University Experiment Station Bulletin 97, 1895. 



