The Avocado: Its Insect Enemies. 29 
great numbers as before, having been hatched from the eggs which 
were not destroyed by the dust. It is essential that the dust remain 
on the foliage for a sufficient length of time after application to de- 
X 
stroy the young mites subsequently hatched. 
A combination of the lime-sulphur concentrate, at the rate of 1 
part to 60 parts of water, plus the 40 per cent nicotine sulphate solu- 
tion, at the rate of 1 to 900 in the diluted lime-sulphur solution, 
proved an excellent spray in killing the red spider, thrips, and lace- 
bug. It also wet thoroughly the branches and killed the young of 
the dictyospermum scale with which it came in contact. The lime- 
sulphur solution in this combination proved effective over as long a 
time as did the lime-sulphur used alone against the red spider on the 
trees. 
CONCLUSIONS RELATIVE TO DUSTING AND SPRAYING. 
1. The dusting method with dry sulphur dust in a finely divided 
form was found to be equally as effective in keeping avocado trees 
free from red spiders as the spraying method with liquid lime- 
sulphur solution. When the red spider is the only pest present in 
the avocado grove the dusting method will prove effective, especially 
at critical times, as it is much the quicker method. It is not necessary 
that the foliage of the avocado be wet with dew in order effectively 
to apply the dry sulphur dust. 
2. Sulphur in any of the combinations used did not control the 
leaf thrips or leafhoppers, but nicotiné sulphate solution when com- 
bined with either lime-sulphur solution or dry dusting sulphur will 
destroy them. 
3. Dry sulphur dust when charged with nicotine sulphate in the 
form of 40 per cent nicotine sulphate and applied to avocado foliage 
was readily removed by heavy dews and light~rains after applica- 
tion. Apparently the addition of the liquid nicotine sulphate caused 
a wettable sulphur. Soon after the first heavy dews, red spiders ap- 
peared on the trees where this material had been used, nothing 
remaining to destroy the young mites as they were hatched from the 
eggs. 
4, Liquid lime-sulphur solution when combined with nicotine 
sulphate proved to be the most satisfactory combination used in 
killing both the red spider and leaf thrips and also the lace-bug. 
The combination remained effective over as long a period as did the 
lime-sulphur alone against the red spider. 
5. Where a grower has a medium sized grove of avocados in which 
a number of insect pests occur, spraying is the more effective method 
in combating the evils with which he has to contend. 
