76 THE EEPOET OF THE ~ No. 36 



-Blackleaf 40, 1 pint, II/2 or 3 pints to 100 gallons was used both alone and 

 with soap, and also in combination with lime-sulphur. One spray was put on just 

 before the blossoms opened, with another just after the blossoms fell, for the 

 apples. Another block was sprayed in full bloom. Pears were sprayed just 

 after their blossoms fell and again five days later. 



Examination of trees directly after spraying showed them to be apparently 

 free from insects, and large numbers of dead nymphs would be found stuck to the 

 leaves by their caudal extremities in the characteristic fashion. Examined two days 

 later, though the block sprayed in full bloom seemed to show best results, all the 

 trees were found to be covered with ])ugs. As laboratory experiments had shown 

 that the material used was quite effective in killing the insect when hit by the 

 spray, even when the weakest strength was used, we knew that the trouble was 

 not in the strength of the spray, or in the manner of its application. 



Observations taken in the sprayed orchards showed large numbers of nymphs 

 ascending the tree trunks. Even in unsprayed orchards it would appear that large 

 numbers of nymphs fall to the ground, shaken off by the high wind or washed oif 

 by the heavy rains. Insects were found in abundance beneath the trees in such or- 

 c'liards or climbing u]^ the trunks. 



In order to determine to what extent nymphs were washed off during spray- 

 ing and v\^hether any considerable proportion of these succeeded in reascending the 

 tree, one large tree was sprayed thoroughly with Blackleaf 40 and soap, after 

 having been banded with tree tanglefoot 3 feet from the ground. Shortly after 

 spraying the trunk of the tree beneath the band was green Avith nymphs. These 

 were counted and removed each day for seven days, and at the end of that time 

 tlie total number of insects captured Ijeneath the band reached the total of 1,389. 

 Large numbers, of course, went up adjacent trees, 538 being taken from one of 

 these. It should be noted here, that this number represents but a very small pro- 

 portion of the insects originally on the tree. By far the greater number were 

 killed and their dead bodies could be found in abundance sticking to the leaves or 

 on the ground. Nevex'theless, where so many thousands were present they were 

 sufficient in number to sting every fruit on the tree and so destroy the crop. 



To determine whether the effect of the spray was merely mechanical or whether 

 the insects that fell were partially overcome by the spray material, another tree 

 was given a strong spray of water with a drive nozzle and at a pressure of 200 

 jjounds. In this case the total for seven days was 308. This shows that there 

 was isomething l)eside the mechanical effect responsible for the large drop from the 

 sprayed tree. This may be due to the insects being hit by the spray, but not suffi- 

 ciently covered to cause death. Again, it may be that the effect of the nicotine 

 fumes is to make the j>ymphs relax their hold and drop to the ground. Laboratory 

 experiments have shown that the fumes of the spray material alone are sufficient to 

 cause death. Nymphs were placed on apple seedlings in cages and at the base 

 was placed cotton 'avooI soaked in Blackleaf 40 at tlie regular strength. The next 

 day the nymphs were dead. 



Experiments were made to determine the distance the nymphs were able to 

 travel and reascend the tree. In an orchard that had not been cultivated for 

 several days, four trees 30 ft. apart each way were banded and 300 nymphs liber- 

 ated midway between them. The next day 17 insects were taken from beneath the 

 tanglefoot band. A similar experiment was tried with 150 bugs in an orchard that 

 had just been thoroughly cultivated. In this case 19 insects reached the trees. 

 The same experiment was repeated in an orchard that was in sod and 300 nymphs 

 liberated. In this case none reached the tree, but could be seen feeding freely 



