172 Insect Pests. 



for the trees were in a most unhealthy state (besides being unculti- 

 vated), having been subject to a bad attack of Winter Moth for two 

 years, and to a worse attack of Tortrix (T. roxana) and Bud Moth 

 (H. occllana), and much Shoot Borer (Blastodacna hcllerclla). Yet 

 the scale had spread much more rapidly on ,the more healthy trees, 

 that were cultivated, than on the unhealthy trees, uncultivated. 



" In January 1905 the whole of the orchards were heavily sprayed 

 with caustic alkali \vash. 



" The proportions used on the whole were : 10 Ibs. caustic soda, 

 10 Ibs. carbonate potash, 100 gallons of water. Unfortunately the 

 owner had sprayed at my advice the whole before the ingredients had 

 been analysed and the percentages were not known. 



" To counteract this some trees on the College farm and some of 

 my own were sprayed with 20 Ibs. of both (98 per cent.) to 100 gallons 

 of water. 



" In all three cases the trees appeared cleaner, but in no case was- 

 any apparent damage done to the scales. 



" Numbers were examined from time to time, and the eggs were all 

 found intact, not a single one being shrivelled or harmed. 



" It was then suggested that lime-washing all the trees would bring 

 the -scale off. Nearly 2,000 trees were thus treated, but some fifty 

 were left as checks. 



" The lime wash was thoroughly well put on by hand, and well 

 worked up to the forks of the branches. Fresh slack lime was used, 

 and put on as a thick wash. Subsequent rains washed much away, 

 but in June I counted 200 trees still heavily coated. 



" This had no more effect than the caustic alkali wash. The only 

 difference noticed was that on the trees washed only with the caustic 

 alkali wash, the eggs hatched out some six or seven days sooner than 

 those which were lime-washed in addition. The lime probably 

 checked the egress of the Iarvn3 mechanically for a time. 



" Neither of these methods of treatment, carried out in three 

 separate places, had any effect whatever upon the Mussel Scale. 



" Mr. Neild of Holmes Chapel wrote me in 1905 in similar strain, 

 stating that he was disappointed with the result of caustic wash for 

 Mussel Scale, and asking advice re paraffin treatment. 



" When most of the ova were observed to have hatched in June, 

 the whole of Mr. Amos' orchard was treated with strong paraffin 

 emulsion. 



" The 2,000 trees were scrubbed with ordinary hand scrubbing 

 brushes, with the wash. Only the trunks up to the forks were 

 treated, except in a few trees. 



