CIRCULAR NO. 20. 



Fie. 3. One of the important wasp-like parasites < Bracon mellitor) of the boll weevil 

 Notice the long ovipositor with which the weevil-infested square is punctured 

 and through which the parasite's egg is forced into contact with the weevil larva. 

 (After Hunter & Hinds, Bui. 51. Bur. of Entomology. U. S. Dept. of Agriculture.) 



When an insect lives like this, at the expense of another insect, 

 it is called a PARASITE, and the insect which suffers is called the 

 HOST. Not all parasites kill their host immediately, but their attack 

 is finally fatal. All insects with the parasitic habit are permanently 

 so and need never be feared as enemies of any field crop. They are 

 always the friends of the farmer. 



It has already been intimated that the BOLL WEEVIL PARA- 

 SITES ARE NATIVE INSECTS. Ordinarily they attack other species 

 of weevils which breed around the cotton fields in different weeds. 

 Most of these other weevils are harmless for two reasons: First, they 

 are held down by their enemies, and, second, they attack and hold 

 down more or less the weeds which are such nuisances. 



It frequently happens that the parasites become so numerous on 

 one of these native weevils that finally the supply of food for their 

 young- gives out. Under such circumstances they find the closely re- 

 lated boll weevil and deposit their eggs on it. EACH YEAR SEVERAL 

 NEW SPECIES ARE ADDED TO THE BOLL WEEVIL ENEMIES 

 by this process, in different parts of the infested region. 



Of the fifteen or sixteen parasites referred to, all do not occur 

 throughout the entire weevil-infested area. In some localities three or 

 four kinds of them are found, in others perhaps five or six kinds, etc. 

 One of the lines of work being conducted by the entomologists is that 

 of distributing these parasites over the entire weevil-infested section 

 so that every locality will have, if possible, twelve or fifteen kinds of 

 parasites attacking the weevil instead of three or four. Some of the 

 co-operative experiments in introducing parasites that have been made 

 in the past season near Shreveport have proved very encouraging and 

 have demonstrated the practicability of this plan. 



If there were no checks in the development of our great pest 

 there would not be a single lock of cotton produced in the infested 

 region. Fortunately there are many checks. In the first place the 

 planter can so manage as to destroy myriads of weevils in the fall, 

 and also so as to kill many hibernating weevils in their winter quar- 

 ters. He can plant early and produce some crop before the weevils 



