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JOURNAL OF ECONOMIC ENTOMOLOGY 



[Vol. 8 



apparent injury. On April 18, 1913, the soil was removed from the 

 base of the trees and a careful examination made for the presence of 

 aphids with the following results: Aphids were found abundant on 

 the roots of all of the treated trees except on two trees treated with 

 tobacco dust at the rate of three pounds per tree; on one tree treated 

 with tobacco dust one and one-half pounds per tree; on one tree treated 

 with lemon oil; on one tree treated with Scalecide and on three trees 

 treated with Electro Pine Tar Creosote. The probable effect of the last 

 three solutions on the life of the tree was a matter of speculation, 

 hence only a very few trees were treated. Only one tree was treated 

 with each dosage of creosote. 



The tests of the efficiency of the Pine Tar Creosote were continued 

 in this orchard on other trees with ample checks. This was the only 

 insecticide continued because, due to the circumstances detailed 

 below, it was considered to hold the greatest promise. These tests will 

 be discussed in a later paragraph. 



During the examination it was found that a small ant was caring 

 for the aphids quite as assiduously as they do for their 3^oung. Wher- 

 ever aphids were found ants were present and they were not present 

 in any case where the aphids had apparently been controlled. 



Upon the removal of the earth from the base of the trees, an ant 

 would seize the nearest aphid in its mandibles and immediate^ seek 

 the shelter of the nearest clod or would follow the channels made in 

 the soil by the roots to what it evidently considered a safe place, then it 

 would hurry back for another aphid and repeat the process. This 

 relationship was found to exist in every case where aphids were present. 



Specimens of the ants were collected and sent to Dr. W. M. Wheeler, 

 who very kindly determined them as Lasius {Acanthomyops) inter- 

 jectus Mayr., supplementing the determination wath the following 

 interesting comments: 



^'This ant is a subterranean species which makes a business, like 

 our other species of Acanthomyops, of dealing exclusively with root 

 aphids and coccids. I have always supposed that these ants did con- 

 siderable harm, because they go into this business quite extensively 

 not only on the root of fruit trees, but also on the root of forest trees 

 and even herbaceous plants. The workers of all the species of Acantho- 

 myops have the curious odor which you noticed and described so 

 well." 



The relationship was so marked that the possibility of controlling 

 the root form of the aphid by control of the ants in this orchard seemed 

 worthy of a test. In other orchards the writer had previously noticed 

 in searching for aphids, the peculiar odor, similiar to that of citronella, 

 that is always associated with L. interjectus. Work was therefore 



