79 



Even g^rantiug that this would be a practical remedy, the winter irri- 

 gation would be likely to cause the death of the vines by inducing 

 growth too early in the season before danger from frost is over. Clean- 

 ing the vineyard completely of all rubbish and leaves in the fall would 

 probably be less expensive in the end; and even then the adjoining 

 lands often could be neither cleaned nor irrigated, and w<mld furnish 

 abundant facilities for the hibernation of the insects. 



It was attempted last summer to kill the hopper at La Mesa, IG miles 

 south of here, by turning on the water and then s})lashing each vine 

 with the view <»f knocking the insects off into it. It met with poor 

 success and was bad on the vineyard besides, by tramping and disturb- 

 ing the soil while in a state of mud. 



It would seem, therefore, that irrigation would be of little use against 

 this insect. It is not at present directed against it, and probably 

 never will be, since kerosene emulsion is much cheaper and more 

 effective. 



The CodliDg Moth {Carpocapsa pomonella) is not yet causing much 

 injury in the vicinity of the station, but is doing so, however, farther 

 north in the Territory. Here is an insect whose life- history is such that 

 it will be considerably affected by an intelligent system of irrigation 

 directed against it. If the water be turned on at the proper season and 

 left for a sufficient length of time, all larva? in fallen apples will be 

 destroyed. This means would doubtless kill by far the most of the 

 brood, si nee only a small proportion of the infested apples, as a gen- 

 eral rule, remain upon the tree. Used in conjunction with the arsenites, 

 this treatment would be of much value. 



The Peach-tree Borer {Sannina exUiosa) does not seem to be affected 

 by irrigation (as noted in Bull. 3, New Mex. Station, June, 1891, p. 14), 

 even though the water be allowed to stand for a considerable time and 

 be given thorough access to the roots. It is probable that the borer is 

 protected by the gummy exudation it causes, which, so far as I have 

 been able to determine, covers the entrance to its tunnel and excludes 

 the water. 



The Green June-beetle {AUorhina mutabilis) would not be amenable 

 to this treatment (as pointed out in Bull. 5, New Mex. Stn., March, 

 1892, p. 11), or would be but very little affected by it in all probability. 

 The grubs often go to a considerable depth and would be practically 

 below reach of the effects of irrigation. Besides there are large as well 

 as small areas of ground in which the insects doubtless breed, situated 

 in i^roximity to cultivated j)ortions which could not well be irrigated. 

 In fact such wholesale irrigation as would be required to destroy this 

 and other insects would consume, at certain seasons of the year, many 

 times the amount of the water which flows down the nearly dry bed of 

 the Eio Grande. 



There is one point which should be mentioned. If found feasible to 

 irrigate extensively at the usual date of issuance of these beetles from 



