April, '15] 



CORY: WOOLLY APHIS 



189 



planned to ascertain the extent to which the ant was present as a 

 symbiote in other orchards, particularly those set in heavier soils than 

 that at Marshall Hall. 



A large percentage of the trees in several of the college orchards have 

 been examined for the presence of the ants. With great uniformity 

 the trees examined showed the presence of L. inter jectus accompanying 

 aphids. Examinations were begun April, 1913, and continued through- 

 out that season. 



With these facts before the writer in regard to the ants and negative 

 results from the tests at Marshall Hall and tests applied in July, 1912, 

 in the college orchards, details of which will be given later, plans were 

 laid for more thorough tests of the Pine Tar Creosote. A row of 

 trees in the Marshall Hall orchard was selected and examined for 

 aphis and ants. Both were found in numbers on every tree. Every 

 alternate tree to the number of seven were treated mth one quart of 

 Pine Tar Creosote after the earth had been removed. Following treat- 

 ment, the earth was replaced. This test was applied on April 26, 1913. 

 Seven untreated trees were left in the row as checks. These tests 

 were examined December 3, 1914, and they showed very encouraging 

 results. The odor of the creosote was decidedly apparent even after 

 twenty-one months had elapsed. Aphids were present on all of the 

 checks except on two and no aphids were present on any of the treated 

 trees except in one case. Ants were not present at the above date. 

 This was to be expected owing to the late date of the observations. A 

 note made in 1912 seems to indicate a congregating habit of the hiber- 

 nating ants. During the early spring a cluster of L. inter jectus was 

 discovered in the cavity of an old tree. This was prior to our observa- 

 tion of the association of the ants with the wooll}^ aphis, hence, no 

 effort was made to keep notes on the cluster of ants. However this 

 nest was just within the border of a wood that adjoins one of the 

 college orchards wherein ants and aphis have since been found in abun- 

 dance. 



Thus far only the tests with undiluted Pine Tar Creosote have been 

 mentioned. No injury to the roots or trees has been observed re- 

 sulting from its use. The material is rather expensive — 30 cents per 

 gallon in quantity, hence tests were made of the material in emulsion. 

 This was made by using two-thirds of a pound caustic soda, 90 per 

 cent (NaOH) for each gallon of creosote. A 6 per cent emulsion 

 was used in the college orchard in July, 1913. Eleven trees w^ere treated 

 in a small orchard consisting of trees grafted on American, Paradise 

 and Doucin stocks. The trees on Paradise stock were only slightly 

 infested with aphids, while those on the other two kinds of stocks 

 w^ere heavily infested. Only a few ants were present. The test was 



