Insect Pests of Interest to Cotton Growers 



199 



aphis, were of no practical importance during the 1918 midsummer 

 outbreak according to the observations of Mr. J. L. E. Lauderdale. 

 Similar observations in regard to lady birds were made by the 

 writer in 1914. The following account^ of the ineffectiveness of 



Fig. 26 — Hymenopterous parasite attacking an aphis. 



Fig. 27 — Parasitized specimens of aphis. 



the lady birds at the time of the first serious outbreak is quoted 

 to emphasize the impracticability of relying upon these natural 

 enemies for the control of the cotton aphis in midsummer : 



"On August 19-20, 1914, a visit by the State Entomologist to 

 numerous cotton fields on both the California and Arizona side of 

 the Colorado River near Yuma disclosed the fact that all kinds of 

 natural enemies were scarce, particularly the lady-bird noted above. 

 In some fields there had been a decrease in the number of aphis due 

 to internal parasites. In several infested fields large numbers of 

 convergent lady-birds had been liberated some weeks previously. 

 Wherever this had been followed by a decrease in the amount of 

 aphis the introduction of the natural enemies was generally cred- 

 ited with the supposed benefits. A close examination, however, 

 showed that these introductions could have had no beneficial effects 

 whatever since the lady-birds in any stage were as scarce in these 

 fields, which had been stocked with the beneficial insects, as in 

 fields which had not been so supplied. Furthermore, an examina- 

 tion of the plants failed to disclose any evidence of the lady-birds 

 having bred in the fields. Such evidence would have been easily 

 found in the presence of large numbers of pupae or empty pupal 



^Sixth Annual Report Ariz. Comni. Agr. & Hort., pp. 37-38, 1914. 



