first year of our experiments with SD-3562, the chemical 

 was not available to us until after June 15. 



On July 6, 1959, following the tests for phytotoxicity, 

 three lots of American elm trees in a nursery, each 

 lot consisting of three trees 3 to 4 inches dbh, were 

 treated by injection with technical SD-3562 at dosage 

 rates of 0.25, 0.5, and 1 ml per inch of tree dbh, fig. 3. 

 To serve as controls, three other trees were similarly 

 treated, except that distilled water was substituted for 

 SD-3562. 



On July 20, three additional trees were treated 

 at a dosage rate of 2 ml technical SD-3562 per inch of 

 tree dbh. As in the previous test, three trees were 

 used as controls. 



An ample supply of bark beetles was obtained 

 throughout the period of the tests from infested wood 

 confined in drums fitted with emergence cages. Only 

 freshly emerged and active beetles were used. 



Cylindrical cages were used to confine the beetles 

 on selected branches of the elm trees. Each cage, 

 constructed of 40-mesh copper wire screening, was 

 about 6 inches in diameter and 18 inches long, with 

 two 15-inch-long muslin sleeves firmly attached to the 

 ends of the copper wire cylinder, fig. 4. A cage was 

 slipped over the end of a branch which had 25 to 30 

 undamaged crotches and was tied in place with twine 



around one of the sleeves. About 25 beetles were 

 counted into a pint carton and transferred promptly to 

 the copper wire cylinder through the open muslin sleeve, 

 which was then tied securely. 



Cages were placed on trees at intervals of 2, 4, 8, 

 and 16 days after the trees had received treatment; the 

 purpose of this procedure was to determine the effective 

 period of the chemical. Each cage, with beetles in it, 

 was left on a branch for 7 days; the branch was then 

 clipped and brought to the laboratory, where the number 

 of beetle penetrations in the crotches was recorded. 

 (A feeding scar, caused by a beetle eating into the 

 xylem, was recorded as a penetration by a beetle.) 



There was little, if any, reduction in beetle 

 penetrations on trees treated at dosage rates of 0.25, 

 0.5, and 1 ml per inch of tree dbh, but there was a 

 definite reduction in the number of penetrations at a 

 dosage rate of 2 ml per inch, table 1. Norris (1959:60) 

 reported the prevention of feeding niches longer than 

 2 mm on trees treated by injection with 20 grams of 

 technical SD-3562 per tree (2 inches dbh); the period 

 of protection lasted for about 21 days after treatment. 

 Later, Norris (1960:1035) reported a significant re- 

 duction in feeding niches with a dosage of 18 grams of 

 the chemical per 3 -inch tree. This second dosage, 

 which approximates 5-0 ml per inch of tree dbh, is the 



Table 1. — Average number of penetrations per beetle in crotches of small elm branches on which bark beetles were 

 confined in cages. The cages, with approximately 25 beetles each, were placed on the branches 2, 4, 8, and 16 days 

 after four lots of three trees each had been treated in July, 1959, with SD-3562 (30-50 per cent alpha isomer) by injection 

 at various dosage rates and left for 7 days; two lots of trees were treated by injection with distilled water only. 



Dosage Rate, 

 Ml Per Inch 

 of Tree DBH 



Penetrations Per Beetle Caged on Branch 

 on Indicated Day After Tree Treatment 



2nd 



4th 



8th 



16th 



0.0 

 0.25 



0.5 

 1.0 



0.25 

 0.38 

 0.26 

 0.30 



0.27 

 0.53 

 0.22 

 0.23 



0.64 

 0.41 

 0.46 

 0.35 



0.55 

 0.79 

 0.78 

 0.45 



0.0 

 2.0 



0.55 

 0.41 



0.82 

 0.25 



1.15 

 0.53 



1.29 



0.44 



Table 2. — The survival time (number of days) of bark beetles placed in jars with twigs from elm trees 2, 4, 8, 16, 

 and 32 days after treatment of trees in July, 1959. Four lots of twigs were from 12 trees treated by injection with SD-3562 

 (30-50 per cent alpha isomer) at various 'dosage rates. Two lots of twigs were from 6 trees treated by injection with 

 distilled water only. 



Dosage Rate, 

 Ml Per Inch 

 of Tree DBH 



2nd 



Survival Time (Days) of Beetles Exposed to Elm Twigs 

 on Indicated Day After Tree Treatment 



4th 



8th 



16th 



32 nd 



: - J2' 



0.0 

 0.25 

 0.5 

 1.0 



6.8 

 5.0 

 2.8 

 3.8 



0.0 

 2.0 



•Average survival time for beetles placed in jars with twigs 2, 4, 8, 16, and 32 days after trees had been treated. 



6.5 

 3.0 



