20 PARASITES OF GIPSY AND BROWN-TAIL MOTHS. 



advised for the destruction of the wheat midge (Contarinia tritici 

 Kirby), namely, burning the debris after thrashing, has only an 

 injurious effect, for, while it is true that the pupae of the midge are to 

 be found in this debris, it should be remembered that the healthy 

 nonparasitized larvae of the midge transform in the ground, while 

 those which remain in the heads are, on the contrary, parasitized. 



Still another method of encouraging parasites is pointed out by 

 Marchal and Silvestri. It is to cultivate in the olive groves various 

 plants upon which allied insects live which are parasitized by the same 

 species of parasites as the olive fly. This idea, independently devel- 

 oped in the United States, has been practically used by Hunter in the 

 fight against the cotton-boll weevil. Allied insects feeding in certain 

 weeds along the borders of the cotton fields have parasites capable of 

 attacking the boll weevil. Careful study of the biology of these allied 

 weevils and of their parasites resulted in the gaining of the information 

 that if the weeds are cut at a certain time the parasites are forced to 

 attack the cotton-boll weevil in order to maintain their existence; 

 actual experimentation has resulted in the very considerable increas- 

 ing of the percentage of parasitism of the cotton-boll weevil in this 

 way. 



THE TRANSPORTATION OF PARASITES FROM ONE PART OF A GIVEN 

 COUNTRY TO ANOTHER PART. 



In 1872 attempts were made by Dr. William Le Baron, at that time 

 State entomologist of Illinois, to transport ApJielinus mali Le Baron, 

 a parasite of the oyster-shell scale of the apple (LepidosapTies ulmi L.) 

 from one part of the State of Illinois to another portion of the same 

 State where the parasite seemed to be lacking. Some slight success 

 was reported, and at the end of the year it was stated that the para- 

 site had become domiciled in the new locality, but, as this parasite 

 subsequently proved to be one of general American distribution, the 

 experiment can not be said to have been worth while except in a very 

 small way. 



In France, F. Decaux, above quoted, in 1872, made some experi- 

 ments in the transportation of parasites from one locality to another. 



Riley, in his third report as State entomologist of Missouri (1870) 

 in considering two parasites of the plum curculio, stated that he 

 intended the following year, if possible, to rear enough specimens of 

 SigalpJius curculionis Fitch to send at least a dozen to every county 

 seat in the State and have them liberated in someone's peach orchard. 

 There seems, however, to be no record that this was ever done. 



In 1880, in his report on the parasites of the Coccidae in the collec- 

 tion of the Department of Agriculture, 1 the senior author called atten- 

 tion to the fact that with the parasites of scales the matter of trans- 



1 Annual Report U. S. Department of Agriculture for 1880, p. 351. 



