DISEASES AND PESTS OF THE MAIZE CROP 441 

 affords them perfect protection from rain or insecticides", chap. 



When the food supply of one plant is exhausted, the larva; 

 leave it and search for fresh plants. 



On reaching maturity, about the first week in January, the 

 larva clears out a portion of the burrow which it has tunnelled 

 into the stalk, prepares an opening through which the adult 

 can escape (Fig. 165, 3), and then transforms to a dark-brown 

 pupa, as shown in Fig. 165, 7, and 7 A. It remains in the 

 pupal stage from a fortnight to three weeks, and then trans- 

 forms to the dark-brown moth. . . . After pairing, the female 

 lays eggs and dies, thus marking the end of the first brood. 

 The eggs for the second brood are deposited under the edges 

 of the leaf-sheaths about the first of February, and may be 

 found anywhere from the main stem well up to the tassel, 

 preference apparently being given to the younger portions of 

 the plant. The eggs hatch about the end of the first week in 

 February, and the larva; burrow into the centre of the stalk as 

 before. They mature by the first of June, depending on the 

 condition of the maize. They do not transform to pupa; at 

 once, as in the first brood, but pass the winter as larvae within 

 the stalks, occurring anywhere from the cob down to the roots, 

 much depending on the size of the plant. . . . Observations 

 . . . lead me to believe that the moths do not travel far in 

 search of food-plants and that they are content to stay in the 

 first maize plant they find {Matty, 1). 



406. Parasites of the Stalk-borer. — Mr. Mally has found 

 a few natural parasites of the maize stalk-borer, but study of 

 their habits led him to the conclusion that " while they do 

 some good, they have not shown themselves able to keep the 

 pest under control ; hence we are forced to adopt artificial 

 means to avoid serious loss ". 



407. Burning the Stalks to Destroy the Stalk-borer. — 

 "From the brief sketch of the life-history of this insect it is 

 apparent that there is no hope of destroying it during the sum- 

 mer by the use of insecticides, because all its transformations 

 take place zuithin the plant, and the moth itself is protected 

 through being nocturnal. . . . Our main hope lies in the pos- 

 sibility of establishing a system of cultural methods which will 

 enable us to prevent injury. . . . The fact that the winter stage 

 of the insect is passed within the remains of its food-plant is 

 its weak point, and gives a control measure in the destruction 



x. 



