186 STATE BOARD OP AGRICULTURE. 



San Jose scale. — Counts were made for the Department of Horticulture of 

 living scales in their test of various sprays against the San Jose scale carried 

 on at South Haven. This involves the examination of the insect under the 

 scale, and the determination of its condition in samples taken before the 

 est is applied and likewise the examination of several thousand individuals 

 after the tests have been made and time allowed for the death of the insect. 

 A process demanding much time and very close observation in each case. 



The potato leaf -hopper. — The summer of 1920 gave us an opportunity to 

 gain more confidence in the efficacy of Bordeaux mixture in the prevention of 

 hopper-burn of potatoes. The Bordeaux acts in no wise as a killing agent 

 but seems to be the best repellent we have tried thus far. I believe that Dr. 

 G. H. Coons, our plant pathologist, agrees with us in taking this view. Fur- 

 thermore, the addition of black leaf forty seems to fortify the Bordeaux and 

 to kill outright those immature hoppers that are hit by the spray at the time 

 of applicatioi), although the general use of black-leaf forty in a crop like pota- 

 toes still remains to be justified by a proportionate money return. 



Grasshoppers. — In the northern half of the lower peninsula and in parts of 

 the upper peninsula, continued all through the summer of 1920 to do serious 

 damage. The use of saw-dust bait seems to be effective and to furnish the 

 greatest benefit for a dollar of any treatment although the bait needs to be 

 prepared according to formula. The substitution of coarse crude poison or 

 of arsenate of lead for the white arsenic is bound to result in disappointment; 

 likewise it is easy to use an over supply of salt, which results in failure since 

 the grasshoppers may get salt enough to satisfy their cravings without getting 

 sufficient of the poison. Last year much difficulty was experienced in getting 

 sufficient poison for the work, owing to a shortage at the time of application 

 and many regions were ill supplied. The price of white arsenic also was high, 

 unless purchased in mid-winter. However, the outlook at present is much 

 brighter since blister-l^eetles whose larvae feed on the eggs of grasshoppers are 

 appearing in goodly numbers in the regions that have suffered the longest 

 and the Legislature of 1921 has generously appropriated the sum of forty 

 thousand dollars for the purpose of refunding to the counties and townships 

 half of the sums used in the purchase and delivery of the poisoned Ijait. It 

 remains now for our county agents and extension, experts to educate the 

 farmers in the use of the bait. 



Codling moth. — During the summer of 1920 an experiment was started 

 looking to the more exact timing of the August spray for the second generation 

 of codling-moth. Cages were established in twelve different stations in 

 various parts of the State and wormy apples collected early in the season were 

 placed therein. The time of the emergence of the adult moths from these 

 cages was noted, both at East Lansing and by the several observers in whose 

 charge they were placed, and the time of spraying to catch the main body 

 of the second generation thus fixed. Furthermore, the time for all jjarts of 

 the State was computed so far as in our power, by means of isophanes or lines 

 connecting equal events in the State. 



These isophanes were corrected so far as our knowledge made possible for 

 elevation and we hope in time to correct for the presence of large Ijodies of 

 water and for soil conditions, together with other disturbing factors. How- 



Isophanes computed by Dr. A. D. Hopkins of the National Bureau of Entomology on a 

 basLs of twenty-five years of observation over the entire United States. 



