Management of Gypsy Moths Using Sticky Trunk Barriers and Larval Removal

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Figure 1.
Relationship between gypsy moth larval density and defoliation in the canopies of individual oak trees. The center line indicates predicted values and the outer lines indicate 95% prediction intervals.

Table 1.

Diameter and canopy area of experimental oak trees and preseason gypsy moth egg-mass density at three sites in Maryland and Virginia.

Site	Mean bole^{^a} diameter (cm)	Mean dripline area (m²)	Preseason egg masses per ha
Harrisonburg, VA	38.7 ±1.4	54.9 ± 6.3	16,275 ±2,957
Pomona, MD	41.0± 1.2	58.5 + 3.9	3,973 ± 963
Vienna, MD	36.2 ± 1.5	77.7 + 6.6	9,806 ± 3,092

Table 2.

Estimated number of gypsy moth larvae and defoliation on oak trees treated with trunk barriers and burlap skirts.

Site	Number of larvae removed per tree ^{^a,^b}	Number of larvae per m²^{^c}	Number of larvae per tree ^{^c}	Defoliation ^{^b}
Harrisonburg	35.4 ± 4.0 a	94.1 ±21.5 a	4,780 ± 2,041 a	14.8 ±5.7 a
Pomona	11.2 ± 3.1 a	83.9 ± 16.7 a	4,908 ± 1,581 a	20.8 ± 4.4 b
Vienna	5.7 ±3.1 a	2I5.O± 17.0 b	17,238 ± 1,610 b	68.4 ± 4.4 c

Values reported are mean + SEM. Means within a column followed by the same letter are not significantly different at a 0.05 comparison-wise error rate.
↵a Includes only trees with burlap skirts.
↵b Data transformed to In (x + 10) prior to analysis.
↵c Data transformed to In (x) prior to analysis.

Table 3.

Estimated number of gypsy moth larvae and defoliation on oak trees treated with trunk barriers and burlap skirts.

Treatment	Number of larvae removed per tree	Estimated number of larvae per m²^{^a}	Estimated number of larvae per tree ^{^a}	Defoliation ^{^b}
Control	0	161.5a	7,943 a	33.7 a
Trunk barrier	0	126.5 b	5,888 ab	23.1 b
Barrier + 1 burlap	9.0	103.3 c	4,169 b	22.4 b
Barrier + 4 burlaps	25.8	132.6 b	6,457 a	25.5 b
	(SEM = 2.8)	(SEM = 10.9)	(SEM = 1,757)	(SEM = 3.0)

Means within a column followed by the same letter are not significantly different at a 0.05 comparison-wise error rate. SEM, standard error of the mean.
↵a Data transformed to In (x) prior to analysis.
↵b Date transformed to In (x + 10) prior to analysis.

Table 4.

Number of gypsy moth pupae and egg masses on oak trees treated with trunk barriers and burlap skirts.

	Number of pupae	Number of egg	Number of egg masses per tree		Egg mass trend
Treatment	below 2 m^{^a}	masses below 2 m^{^b}	Preseason ^{^b}	Postseason ^{^c}	(Post/pre-season)
Control	9.6 a	36.5 a	45.1 a	235.9 a	5.2
Trunk barrier	39.2 b	48.8 a	34.8 a	168.3 a	4.8
Barrier + 1 burlap	64.9 c	59.2 b	31.5 a	145.9 a	4.6
Barrier + 4 burlaps	143.7 d	90.5 c	39.8 a	211.0a	5.3
	(SEM = 13.2)	(SEM = 16.6)	(SEM= 6.0)	(SEM = 53.6)

Means within a column followed by the same letter are significantly different at a 0.05 comparison-wise error rate. SEM, standard error of the mean.
↵a Data transformed to In (x + 5) prior to analysis.
↵b Data transformed to In (×) prior to analysis.
↵c Data transformed to In (x + 1) prior to analysis