THE PEACH-TREE BARKBEETLE. 105 
periments 29, 30, and 31 failed to give any beneficial results, the 
emulsion being very poor, as the oil became partly separated from the 
mixture before the latter could be applied. Experiments 32, 33, 34, 
85, 36, and 37 gave only negative results, neither killing the beetles in 
the burrows nor repelling later attacks. In experiment 38 a plat of 
100 trees was used. Fifty of the trees were very severely cut back and 
4 or 5 of them, being too weak to recover, died. The other 50 trees 
were sprayed with lime-sulphur wash. At the end of the season the 
pruned trees had produced a strong, healthy foliage and the beetles 
were attacking them but little. The untrimmed trees were badly 
attacked and had thrown out a scant, sickly-looking foliage. Experi- 
ment 39 gave satisfactory results. All of the beetles in the trees at the 
time of application were killed and no more settled on them until 
about the last of September; then, a few having settled, the trees were 
whitewashed and further injury was stopped. The cost of this treat- 
ment, as made here, prevents it being practicable for a large orchard 
unless the amount of material used can be reduced with equally good 
results for the weaker emulsion. Experiment 40 showed that the 
beetles attack the trees in which these cut branches were placed with- 
out settling on the cut branches. Experiments 41, 42, and 43 showed 
the most practicable, and at this time the most likely remedies. These 
are the combinations of a whitewash and an oil, the whitewash 
probably being the main factor in repelling the beetles. The cost of 
these experiments was 11 cents per tree for each application. The 
trees in these plats, while not entirely free from further attack 
during the season, suffered considerably less than surrounding plats 
of trees. 
METHODS OF CONTROL. 
Pending further investigation, the following treatments are sug- 
gested as being practicable and to a certain degree favorable: 
For trees seriously injured.—Severely trim back the trees and apply 
barnyard manure or commercial fertilizers; then apply a thick coat 
of whitewash three times a season, the first application to be made the 
last week in March, the second application during the second week 
in July, and the third application about the 1st of October. 
For trees apparently healthy but slightly attacked—Paint the 
trees with a thick coat of whitewash three times each season as in the 
previous treatment, applying it to the trunks and larger limbs. The 
whitewash applied at the times specified will act as a repellent, the 
emergence of the beetles being slightly later than the dates given for 
the different applications. Add one-fourth pound table salt to each 
pail of whitewash, thus making the latter more adhesive. All of the 
dead or nearly dead limbs and trees should be removed and burned as 
fast as they appear in an orchard, as this will destroy the breeding 
places. 
10090— Bull. G8—O09 
8 
