THE SUGAR-CAFE MOTH BORER. 39 



PARASITES AND PREDACIOUS ENEMIES. 



MOTH-BORER ENEMIES IN THE "UNITED STATES. 



Four parasites of species of Diatraea have been found in the United 

 States, but three of them are extremely rare. The chalcis-fly Tricho- 

 gramma minutum Riley is universally distributed in the sugar-cane 

 fields of Louisiana and of the lower Eio Grande Valley of Texas, 

 and is a very important factor in the control of the moth borer. It 

 is a minute wasplike insect, the female of which deposits her eggs 

 within the eggs of the borer, in the course of a few days numbers of 

 adult parasites emerging from the moth-borer eggs. 



A similar insect is the black parasite Ufens niger Ashmead, 

 found near Brownsville, Tex., by the senior writer in 1912. This has 

 not been found a second time, although Mr. George N. Wolcott made 

 a special search for it extending over about two months in the sum- 

 mer of 1917. Vickery x records it as a common parasite of eggs of 

 the leafhopper Draeculacephala mollipes Say, and it may attack 

 Diatraea only rarely. 



Parasites of the larvae have not been found in Louisiana, but a 

 braconid, Microg aster sp., has been reared from larva? of. Diatraea 

 zeacolella Dyar, collected in corn by Mr. E. R. Barber at Bennetts- 

 ville, S. C. A thorough search for larval parasites was afterwards 

 made in South Carolina, Georgia, and Florida by Mr. A. G. Davis 

 and the junior writer, but none was found. 



Another braconid has been reared by Dr. A. W. Morrill, State 

 entomologist of Arizona, from the species of Diatraea (probably 

 lineolata) which occurs in that State. 



Stubbs and Morgan (152) record a telephorid beetle, Chauliogna- 

 thus marginatum Fabricius, as feeding on the larvae. This is oc- 

 casionally found in considerable numbers in sugar-cane fields in 

 Louisiana. 



During 1916 Mr. A. G. Davis found earwigs (Dermaptera) con- 

 suming larvae of Diatraea in Florida, and in 1917 Mr. George N. Wol- 

 cott, in Texas, observed them feeding on eggs of Diatraea saccharalis 

 which had previously been parasitized by Trichogramma minutum. 

 It is unlikely that the work of earwigs is of any importance in con- 

 trol, and in feeding on parasitized eggs they would, of course, do 

 more harm than good. 



The Argentine ant {Iridomyrmex humilis Mayr) has been ob- 

 served feeding occasionally on eggs, larvae, and pupae of the moth 

 borer, but it can not be considered a factor in repression. The ants 

 seem to attack only those eggs which have been parasitized, and while 

 they may sometimes attack larvae they will not ordinarily molest a 



1 Gibson, Edmund H. The sharpheaded grain leafhopper. U. S. Dept. Agr. Bui. 254. 

 16 p., 1 fig. 1915. 



