FIKIJ) WOUK — RELEASE OF PARASITES. 



25 



high hedge of Ambrosia trifida with scattered Solanum rostratutn. 

 As ;i Further check od the experiment the nearest part of this field 

 ("D," fig. 5) was examined and proved to be parasitized by 2.1 per 



cent less than "A." On the contrary, the farther part of the held 

 (•• K," fig. 5) showed 5.8 percent higher parasitism than ''A." The 

 conclusion was that "E" and "])" did not influence "A." 



The results are given in Table XIV for the entire experiment, and 

 also according to species. Ii is believed by the writer thai it was the 

 release of Bracon meUitor which accomplished the change. 



The evidence upon which this belief is founded is both positive 

 and negative. Bracon meUitor was not found breeding upon any 

 other species of weevil in the vicinity, and yet the examinations 

 showed an increase of parasit i/at ion by this species iu the " parasite 



I ■']<,. .">.— Diagram of cotton plantation of II. O. Samuel, Dallas, Tex., of G4*4 acres, showing location 

 of plats where observations and experiments on boll-weevil parasitism were made. (Original.) 



area" opposed to a decrease in the " check area." Catolaccus incer- 

 tus, although released in large numbers, did not take hold at all, nor 

 was it found breeding upon any other species of weevil in the vicinity. 

 A few Ceramhycobius cyaniceps were released, but the only trace of 

 parasitization by this species was found in the original check. And 

 yet this species was bred from Lixus musculus in the stems of Poly- 

 f/oiii/m pennsylvanicum near by, and also from Triclwbaris texana 

 Lee, in the stems of Solanum rostratum adjacent to "A". No 

 Eurytoma tylodermatis were released, although this species was abun- 

 dant throughout the field. It is known as a parasite of Lixus scro- 

 bicoUis Boli., which breeds in Ambrosia trifida stems. Immense 

 numbers of this plant were growing along the road adjacent to "A." 

 In order to show thai plat " K," which was highly parasitized by 



