No. 6. DEPARTMENT OF AGRICULTURE. 741 



held over the "bud of the plant. There is no reason for coating the en- 

 tire plant if the work is done at the right time. 



The arsenite should be mixed with a material that becomes sticky 

 when wet. There is nothing better than wheat flour, and a damaged 

 or low grade lot usually can be bought for a small sum. The mixture 

 should be strong — one jjound of Paris green to sixteen pounds of 

 flour — which is a sufficient amount for treatment of an acre of rather 

 large vines. When the tops are small, and there are few branches, 

 a less amount is sufficient, and an active boy can make the applica- 

 tion to two acres in a day. 



Lime is generally UfSed as a diluent when applying arsenites in a 

 dry form, III it is undesirable because it will not hold the poison 

 on the vines during a rain, while flour will do so if set by a dew or 

 mist. There are seasons in which a second treatment of this mixture 

 becomes necessary, but they are the exception. If cold weathei* 

 jirotracts the time of hatching, or if the rains are very heavy, one 

 treatment may be found insufficient, but our experience is such that 

 we expect one application, properly made, to suffice, and the ex- 

 pense per acre seems slight when it affords immunity from this pest 

 for the season. The secret of success with it lies in having the mix- 

 ture strong, and placing it where all the grubs go soon after hatching. 

 It lodges in the new leaves of the stalk, and the grubs that hatch later 

 find it and drop off unnoticed. I am commending the plan only to 

 Ihose who have a small acreage, knowing that most growers on an 

 extensive scale will prefer the sprayers on account of the rapidity of 

 the work. When the Bordeaux mixture is being applied for blight, 

 the arsenite for tdie potato beetles or grubs is put into it. 



The arsenite should be dissolved in a small amount of water be- 

 fore it is added to Bordeaux mixture. A convenient wav is to use 

 a large bottle so that the water and arsenite can be thoroughly agi- 

 tated. 



Parasitic Enemies of the Beetle. — There is constant increase in the 

 enemies of the Colorado beetle, and this is in accordance with the 

 law of nature that maintains a sort of balance in the insect world. 

 When any one species increases out of due proportion, a natural 

 check of some sort is usually provided. Several species of insects 

 prey upon the eggs and upon the grubs of the beetle. In some years 

 they are so numerous in sections of the country that no grubs can 

 reach maturity. This was observable in the season of 1902 in my 

 own fields, rendering any application of arsenites unnecessary. An- 

 other season these enemies of the beetle may be less numerous here, 

 and we should not expect entire immunity from attacks of the Colo- 

 rado beetle through such agencies, but it is probable that there will 

 be increase of these insects. 



The Flea Beetle. — An immense amount of injury is done to the 



