MITES WHICH ATTACK THE WEEVIL. " 43 



and 1 hyperparasite. Among these 46 predators are 6 which also 

 prey upon the boll weevil. At least 1 very common predatory 

 insect is known to prey upon many of the boll- weevil predators. 

 Fifty-five species of weevils are known to be attacked as cohosts of 

 26 species of parasites and of the 19 species of predators which attack 

 the boll weevil. These 55 species of weevils are known to breed 

 upon 91 species of plants, most of which are to be found in the vicinity 

 of the cotton fields. Three of these weevils sometimes breed upon the 

 cotton plant. Among the great number of parasites which attack 

 the 55 cohost weevils, 44 species are definitely known to science and 

 at least 6 species of hymenopterous parasites are known to attack 

 these 44 species of parasites. Tliis complexity could be carried still 

 further, but probably enough has been stated to show how the many 

 influences of nature are dependent upon one another. The state- 

 ments are illustrated graphically in the accompanying diagram (fig. 6). 



The principal point of importance in all of these facts is that the 

 boll weevil has been deriving its parasites from these 51 species of 

 weevils and from other weevils which are not known to us, and 

 there is every reason to beheve that some of these other 44 species 

 of parasites, or still additional ones to be discovered, may be drawn 

 over to the boll weevil as parasites in the future. The weevils serv- 

 ing as cohosts and the parasites are listed in the accompanying table 

 (fig. 7) in such manner as to show the nature of the interrelationships. 



It will be noticed from this table that 6 weevils, namely, Laria 

 sallsei, Laria exigua, Smicraulax tuherculatus, Anthonomus albopilosus, 

 Tyloderma foveolatum, and Trichoharis texana each have 4 of the 

 boll- weevil parasites; 4 weevils are attacked by 3 of the parasites, 

 15 of the weevils by 2 parasites each, and the remaining 37 by only 1 

 parasite each. 



Of the parasites, Ceramhycohius cyaniceps attacks 18 hosts, Eury- 

 toma tylodermatis attacks 16 hosts, Catolaccus incertus 14, Catolaccus 

 Jiunteri 13, and Microhracon mellitor 12. These 5 parasites are also 

 regarded as the most important parasites attacking the boll weevil 

 itself. Perhaps this importance is due to the fact that they have 

 a larger number of native hosts and are hence in greater abundance 

 around the cotton fields than the parasites having fewer native 

 hosts. . 



3. MITES WHICH ATTACK THE BOLL WEEVIL. 



ACARINA. TARSONEMID^. 



The mites of the genus Pediculoides are assuming an important 

 role among insect parasites, two species being accredited to the 

 boll weevil. 



