368 



notable Ohio broods of the periodical cicada [Tibicen septemdecim], 

 and the soil maps of Ohio published by the U.S. Bureau of Soils. 

 From this the inference has been drawn that the nature of the soil 

 must be a potent factor in determining the limits of several Ohio 

 broods, since the western limiting line of the 1897 broods exactly 

 corresponds with the line dividing the western dolomitic limestones 

 from the eastern sandstones and shales. The question of drainage 

 and soil temperature operating at a critical stage such as pupation 

 may perhaps have some bearing on the problem, as the underground 

 drainage in the east is much poorer than in the west, resulting in a 

 lower spring temperature of the soil, though exceptional spots occur 

 east and west of the line without affecting the distribution of the 

 cicada. Another possible factor may be the presence of Imie in the 

 soil, affecting chitin formation, directly or indirectly. 



As to the theories of brood formation, the suggestion has been made 

 that local glacial conditions may have retarded the development of 

 the species for different periods in different localities ; another view 

 is, that new broods have been made by splitting off from the main 

 broods, and another, that environment has caused the appearance 

 locally of a new brood earlier or later than the original one, which 

 might be left to hold the territory alone or become the predominant 

 one should some accident in the course of years happen to the parent 

 brood in that locality. Such conditions as variation in climatic con- 

 ditions, geological changes, or changed topographical conditions of the 

 country, including the character of the vegetation, might conceivably 

 result in the acceleration or retardation of entire broods of this insect. 



King (J. L.). The Peach Tree Borer. —Mthly. Bull. Ohio Agric. ExpL 

 Sta., Wooster, ii, no. 1, January 1917, pp. 23-28, 2 figs. [Received 

 19th June 1917.] 



Aegeria (Sanninoidea) exitiosa, Say (peach-tree borer) is the most 

 important insect enemy of the peach east of the Rocky Mountains. 

 The moths attain their maximum prevalence about mid-August, an 

 average of 400 fertile eggs being deposited by each female. The 

 larvae bore into the base of the trunk by way of the crevices in the 

 bark, and become established below the level of the soil. A single 

 larva may cause the death of a small tree by girdling the base of the 

 stem, thus cutting off the sap supply. In bad cases as many as 30 

 larvae may inhabit a single tree. After numerous experiments with 

 insecticides and mechanical protectors, the only efficacious method of 

 control seems to be that of " worming " or cutting the larvae out of 

 their burrows by means of a sharp knife. This process, which requires 

 great care and skill, should be performed in the autumn during October 

 or November, and again early in the summer, between the first and 

 10th June. 



The soil should be hoed away from the base of the tree to a depth 

 of 6 inches, so that the larvae may be located by the exudation of 

 gum and the presence of sawdust. After the larvae have been removed 

 and killed, the soil should be replaced in a mound 6 to 8 inches high 

 round the trunk as a protection from fresh infestation, and left until 

 the second operation in October, when the mounds should be removed 

 so that the trees may harden for the winter. 



