312 JAMES W. McCOLLOCH AND H. YUASA 



attempts fail to bring about actual oviposition. The artificial 

 method whereby the inverted eggs may be secured has been 

 already described. The same result may be realized when the 

 leaf is long and bends over, and the female alights beyond the 

 bend with her head towards its base The base in this situa- 

 tion will be higher than the tip of the leaf. This mode of oviposi- 

 tion and the orientation of the egg will be here designated as 

 inverted. (3) The eggs may be laid transversely or at varying 

 angles with the long axis of the leaf. It is only necessary to 

 mention that the three conditions described above are capable 

 of modifications and also that they can be realized on the lower 

 as well as on the upper surface of the leaf. 



A series of experiments with eggs laid according to the methods 

 stated above were performed, in connection with which more 

 than three hundred larvae were studied and their behavior 

 recorded. In no instance was the orientation of the larvae, 

 soon after hatching, not in accordance with the expectation. 

 Every one of the three hundred and more larvae turned towards 

 the caudal end of the egg regardless of the manner of oviposi- 

 tion, position on the leaf, and in cases of inverted oviposition, 

 regardless of the fact that this orientation leads the larvae away 

 from the only possible feeding place, namely, the base of the 

 leaf-sheath. 



Migration of Larva on the Leaf. — The direction of movement, 

 as has been stated, is predetermined by the orientation of the 

 egg itself, and is not in any way influenced by the condition 

 of the leaf upon which it is laid. After the initial orientation, 

 the larva usually starts without delay on the journey down the 

 leaf, following the first or second grooves adjacent to the one 

 in which the egg was located. The movement is subject to 

 variation in regard to the rate of progress, although generally 

 it is a slow process. The larva may move continuously or it 

 may rest now and then. When it reaches the base of the leaf 

 or the ligule, it crawls up the latter, squeezes in between the 

 leaf-sheath and the main stem, and continues its way down- 

 ward to a point just above the joint or origin of the culm. In 

 the case of inverted oviposition, the larva, on hatching, turns 

 toward the tip of the leaf and this is the direction of its pro- 

 gress It works its way slowly up the leaf, against the force of 

 gravity, and constantly subjecting itself to danger of various 



