INSECT PESTS OF OHIO SHADE AND FOREST TREES 235 



"Derostenus primus How. A chalcid reared from egg masses, 

 but is thought to be a secondary parasite of Tricho gramma 

 odontota." 



"Sympiezus uroplatae How. A hymenopterous parasite, the 

 white larvae of which was found feeding externally upon the larvae 

 of C. (O.) .dor sails." 



*' Spilochalcis odontotae How. Seen emerging pupa of C. (O.) 

 dorsalis. This is an internal parasite. 



*' Ichneumon hispa Harris. Bred from pupa of C. (0.) 

 dorsalis.'* 



Control. — ^It is possible to protect plants from injury by this 

 species by spraying with arsenate of lead at the rate of 3 or 4 pounds 

 of the paste or 2 pounds of the powder to 50 gallons of water when 

 the adult beetles are abroad and feeding on the leaf surfaces. The 

 fact that the larvae leave old mines and construct new ones also 

 contributes to the feasibility of spraying with poisons, since some 

 of the leaf surface is consumed when the new mine is started, and 

 in all instances which the writer has observed the entrance to the 

 mine was made on the upper surface of the leaf. 



In the spring of 1912 the writer successfully protected apple 

 trees near Marietta by the use of arsenate of lead, but to this was 

 added a small amount of sorghum molasses. The formula used was 

 as follows: 



Water 40 gallons 



Sorghum molasses V2 gallon 



Arsenate of lead iV2 pounds 



Laboratory feeding tests confirmed the field results that the 

 beetles could be destroyed by the use of arsenate of lead applica- 

 tions and indicated that slightly weaker strengths could be em- 

 ployed. The molasses undoubtedly contributes to the efficiency of 

 the spray but may not be essential. 



Spraying with poisons, however, is practicable only under very 

 limited conditions, such as in the instance cited where valuable fruit 

 trees were to be protected or in the case of prized ornamentals. It 

 is obviously impracticable to attempt a general application of poison 

 where entire hillsides of black locust are attacked ; indeed, in such 

 cases there is no practicable control method to use. Clearly it 

 is impossible to clean up the forest floor during the winter and 

 spring with the intention of collecting the hibernating beetles, first, 

 because of the labor involved and, second, because there is a ques- 

 tion as to whether the removal of the natural protection and source^ 

 of fertility might not be quite as harmful as the work of the beetles* 



