THE TERRAPIN SCALE. 73 



not satisfactory when applied against the terrapin scale in the winter 

 season. 



In the spring of 1913 6 sprayings were made to test the efficiency 

 of commercial miscible oils to which a wax solvent had been added. 

 Accordingly experiments 8, 9, 10, 11, 12, and 13 were made and the 

 sprays were applied in connection with the sprayings in experiments 

 1 to 7. It is to be noted that the spray used in experiment 8 was 

 quite effective as a scale destroyer and that only a small amount of 

 spray injury resulted. It serves, by contrast with experiment 4, to 

 show that oils which are dangerous and ineffective when applied in 

 winter may be applied with success in the spring. Particular atten- 

 tion is called to the effective work done by miscible oil when used at 

 the rate of 1 gallon to 20 gallons of water in experiment 9. Where 

 gasoline was added to the miscible oil there was a decided loosening 

 of the scales, and many of the dead scales fell before the count was 

 made, while comparatively few fell where miscible oil was used 

 alone. This condition was noticed at the completion of the count, 

 and comparisons were then made of the number of living scales in 

 the plats having miscible oil only, in contrast with those having 

 both miscible oil and gasoline, with the result that in all cases fewer 

 living scales were found upon the twigs treated with the spray con- 

 taining gasoline than upon those having miscible oil alone. It is 

 therefore concluded, regardless of the count, that miscible oils are 

 improved as a spray by the addition of gasoline emulsion. 



Experiment 14 was made in Mr. A. Newcomer's orchard near Mid- 

 vale, Pa., November 6, 1913, to determine the effect of a miscible oil 

 and gasoline mixture when applied in the fall just after the leaves 

 had fallen, and 15 trees were sprayed for comparison with the same 

 percentage of miscible oil, but without gasoline. Unfortunately it was 

 not possible to make a scale count until March 31, 1914, when many 

 of the dead scales had fallen. Infested limbs upon the check trees 

 were compared with similar branches on the trees in experiment 14, 

 and these comparisons showed that the formula was more effective 

 with gasoline than without it. The spray injury in this experiment 

 was slight and the treatment was moderately efficient. All of the 

 experiments made March 28 and 29, 1913, were finally rated as effi- 

 cient, except No. 13, where the spray was deficient in oil. It is the 

 author's belief that miscible oil — while not as desirable as linseed-oil 

 emulsion, which is treated later — can be used with safety when 

 applied just before the buds open, in dilutions of 1 gallon in 16 to 20 

 gallons of water. It is very effective, especially when the oil is 

 mixed with one-half its volume of gasoline (emulsified). The natural 

 mortality in the Newcomer orchard for the winter of 1913-14, as 

 determined by a scale count from unsprayed trees, was 55.01 per cent. 



