THE OUTBREAK OF 190*7. 37 



fields of fall oats and more or less volunteer grain in other fields, all of which consti- 

 tuted breeding grounds for the pest during the preceding autumn, and from which 

 winged individuals migrated and established new colonies in other fields; these, 

 owing to influence of weather on the development of parasites, caused the most of the 

 injury in wheat. 



We received a letter with specimens from Mr. L. M. Smith, Mr. 

 Sherman's assistant, at Newport, Carteret County, N. C, stating that 

 he found a small field of oats in the outskirts of town that was 'con- 

 siderably damaged by Toxoptera. This county is on the coast and 

 Newport has an elevation of 19 feet. From this it seems that in all 

 probability Toxoptera covered the entire State. 



The senior author also found Toxoptera in destructive abundance 

 at Midlothian, Chesterfield County, Va., in a small meadow of orchard 

 grass. Mr. J. L. Phillips, the State entomologist, reported a slight 

 outbreak at Cloverdale, Botetourt County, Va., in rye, and stated 

 that considerable damage had been done in some parts of the field. 

 One undetermined Aphidius was found at Midlothian, while none was 

 reported from Cloverdale. 



There was an outbreak of Toxoptera in the bluegrass lawns north 

 of the buildings of the Department of Agriculture at Washington, 

 D. C, in July, 1907. The infested area (see PL II, fig. 2) was appar- 

 ently confined to the space of about an acre, where it was excessively 

 abundant; outside of this area practically no Toxoptera could be 

 found. This offered a good opportunity to test spray materials and 

 a number of experiments of this kind were carried on. 



Dr. Howard, personally, found Aphidius present in this infested 

 area though in very limited numbers. In all probability this was 

 Aphidius avenaphis Fitch, as we have since found this species in this 

 exact locality but at no time have we found A. testaceipes Cress., 

 which, until Mr. Viereck revised this group, had been considered to 

 be Lysiphlebus tritici Ashm. We did not, in 1907, find any species of 

 Aphidius present and did not know that Dr. Howard had done so, as 

 he soon after sailed for Europe and at the time Circular 93 of this 

 bureau was published the statement as to its nonoccurrence was not 

 called to his attention in time to be corrected and he did not inform 

 us of his find, supposing that we knew of it already. Mr. Kelly, how- 

 ever, found Allotria sp. present there in 1907, and we have since found 

 this to be a parasite of Aphidius, which may account for the fact that 

 the latter was present in such limited numbers. In 1908 Aphidius 

 avenaphis was quite plentiful there, although specimens were not 

 preserved, while Allotria sp. was found sparingly on the grounds else- 

 where in the vicinity. As Toxoptera attracted no attention in this 

 area on the grounds of the Department of Agriculture in 1909 we 

 have no records for that year. In 1910 Toxoptera was again injuri- 

 ously abundant on the same area and no Aphidius could be found, 

 while Allotria sp. was still in evidence. It seems possible that condi- 



