No. 4.] mjUEIOUS INSECTS. 163 



and the potato bugs were about as lively after I had applied 

 it as before. I had to go over the vines with Paris green. 



Professor Fernald. I have stated some proportions in 

 the paper which I did not read. In buying this commercial 

 material, you must have the proportions given. There are 

 two qualities of acetate of lead (the material to be mixed 

 with arsenate of soda to make arsenate of lead) on the mar- 

 ket. One has 50 per cent of arsenic, and the other has less. 

 It is the fifty per cent which these conclusions are based on. 

 In following the rules I have given, please observe the pro- 

 portions, and insist on getting the fifty per cent quality. 



Question. Does this arsenate of lead come in a suitable 

 form to be applied dry with one of those guns ? 



Professor Fernald. So far as I know, it is not on the 

 market in shape to be used dry ; but if there is a demand for 

 it, I have no doubt that there are people who will eventually 

 supply the demand. 



Question. Is the formula in any of the bulletins of the 

 Hatch Experiment Station? 



Professor Fernald. It has been published there, in the 

 report of the gypsy moth department and also in the news- 

 papers. 



Mr. Pratt. Is it easy to detect this San Jose scale ? 



Professor Fernald. It is not easy ; you can scarcely see 

 them. 



Mr. Taber. Have you used the arsenate of lead in con- 

 nection with the Bordeaux mixture? 



Professor Fernald. I do not think it has been tried. 



Mr. Morse (of Medway). Will arsenate of lead kill the 

 larvae of the potato beetle ? I tried it, with unsatisfactory 

 results. I put it on according to the formuhi issued by the 

 experiment station. After waiting a day or two, I put it on 

 stronger ; then I put on Paris green. 



Professor Fernald. Your potato beetles must have a 

 very different constitution from what they do at Amherst, 

 for I have killed them very easily. There is this about 

 arsenate of lead : You can use it in any proportion you 

 like, and not be afraid of hurting your foliage. Perhaps 

 you did not use it strong enough, or there might have been 

 some fault in the chemicals or in the way you prepared it. 



