726 



SCIENCE 



[N. S. Vol. XLII. No. 1090 



periodicals especially devoted to the particular 

 subjects, or in publications which have wide 

 circulation and are well known to habitually 

 publish such papers. If all publishers and 

 naturalists would take the same position it 

 would surely greatly simplify the work of the 

 future systematist. Junius Hendekson 



THE EFFECT OF CYANmE ON THE LOCUST-BORER 

 AND THE LOCUST-TREE 



During the past five years a number of ex- 

 periments have been made from the office of 

 the Illinois state entomologist with methods for 

 destroying the black locust-borer (Oyllene 

 rohinw). From articles appearing in Science 

 during the last few months, especially those by 

 Professor Fernando Sanford in the issue of 

 October 9, 1914, and by Professor C. H. 

 Shattuck in the issue of February 26, 1915, 

 it seemed probable that at least a part of the 

 borers in infested locust-trees might be killed 

 by introducing small amounts of potassium 

 cyanide into the trunk and bark. 



Early in the spring of 1915, fifty black locust- 

 trees, fourteen in a small grove at Athens, in 

 central Illinois, and thirty-six in a large plan- 

 tation at Union Grove, in northwestern Illi- 

 nois, were treated with potassium cyanide and 

 sodiiun cyanide in the following manner: 



The trees selected were from one to seven 

 inches in diameter and were nearly all badly 

 infested with the larvse of the locust-borer. 

 The borers were still in their overwintering 

 cells in the bark, but were just becoming active 

 at the time. The cyanide was placed in the 

 trees in auger-holes of one fourth, one half, 

 three fourths, and one inch diameter, bored at 

 different heights from the ground and differ- 

 ent depths into the trunk. The amounts of 

 cyanide used in single trees varied from one 

 twentieth to one half an ounce. The chemicals 

 used were potassium cyanide, 98 per cent, pure, 

 in small lumps, and cyanide-chloride carbonate 

 mixture in granular form, guaranteed to con- 

 tain 35-38 per cent, sodium cyanide. After 

 the cyanide had been placed in the trees, the 

 auger-holes were tightly plugged with corks 

 driven in with a hammer. 



The fourteen trees at Athens were treated 

 March 12, and the thirty-six trees at Union. 

 Grove, April 1, 1915. The results of the treat- 

 ments were taken at Union Grove July 13 

 and at Athens July 15, 1915. 



The results of this experiment showed no 

 benefit by the treatment. Of the fifty trees 

 treated, eight could not be located in the 

 summer, owing to the dense growth of weeds 

 and sprouts. The treatment of these eight 

 trees did not differ materially from that given 

 the forty-two examined, and could not have 

 made any marked difference in the results. Of 

 the forty-two trees examined in July, twenty- 

 three were dead and nineteen alive. Of the 

 nineteen living trees, all but three contained 

 living larvse of Cyllene robinoe. In several 

 cases living borers were found directly above 

 and within six inches of the auger-holes, and 

 in three cases the borers were within one inch 

 of the auger-holes. Not only were the borers 

 alive in the living trees, but in all cases where 

 the trees had put forth leaves in the spring of 

 1915, living borers were present in numbers 

 in the trunks, and could be found around the 

 bases of the trunks of many of the trees that 

 had not shown foliage the past spring. Not 

 a single dead borer was found near the points 

 where the cyanide had been placed. 



While over half of the trees treated were 

 dead, this was not entirely due to the effects of 

 the cyanide, as at least twenty-five per cent, 

 of the untreated trees in both groves had died 

 from the effects of borer injuries. There can 

 be no doubt, however, that the cyanide had a 

 very injurious effect on the trees, as in all the 

 living trees the bark was dead and the wood 

 discolored for a greater or less distance around 

 the holes where the cyanide had been placed. 



It was an interesting fact, which has, how- 

 ever, no bearing on the effect of the cyanide on 

 the trees, that some rodents, probably rabbits, 

 had gnawed many of the trees around the 

 auger-holes, deeply scoring the wood. There 

 was no residue from the cyanide in any of the 

 auger-holes when examined in July, whether 

 the corks had been removed or not, and no odor 

 of the cyanide could be detected in the wood. 



