Pitch moth (Lepidoptera) Abundance, Damage and Management

At the Prince George Tree Improvement Station

Lynn A. Rocchini, B. Staffan Lindgren, and Robert G. Bennett

Relative Distribution and Abundance of Species (Synanthedon)
Using traps baited with the pheromones (Z,Z) -3,13-octadecadien-1-yl acetate or (Z,Z) -3,13-octadecadienol , we established that the Douglas-fir pitch moth, S. novaroensis, is the only sesiid pitch moth species causing damage in seed orchards at PGTIS. No sequoia pitch moth, S. sequoiae, the species previously assumed as the damaging agent, were caught. Emergence traps placed over pitch masses in the lodgepole pine provenance trial at PGTIS showed that the primary pitch moth species was the western pine moth, Dioryctria cambiicola (Lepidoptera: Pyralidae).

Several other sesiid moth species of interest were caught. Synanthedon culiciformis, a species attacking alder and birch, were caught in the traps baited with (Z,Z)-3,13-octadecadien-1-yl acetate, as were S. canadensis, a species previously only known from Alberta and Utah. Sesia spartani, a species previously only found in Michigan, was caught in traps baited with (Z,Z) -3,13-octadecadienol.

Douglas-fir Pitch Moth,
S. novaroensis
(Photo: L.Friskie)
Orchard Damage Survey

A survey of four orchards were for old and fresh pitch moth attack was conducted during July and August of 1996. Each pitch mass was counted as one attack. Clone number, diameter at breast height, vigour, and gaps (the number of missing trees surrounding the tree), were also measured and recorded for each tree. In all four orchards, clone significantly affected the probability of any tree in the orchard being attacked by pitch moth in the presence of all other variables (P<0.005). Tree location and diameter at breast height (DBH) were significant in three of the four orchards (P<0.05). In two of the four orchards, the presence of previous pitch moth attack had a significant effect on the probability of any tree in the orchard being attacked (P<0.05). The significance may be due to pitch masses on the tree containing attractive resin volatiles, or an inclination of the female moth to simply oviposit on the same tree from which she emerged.

Western Pine Moth,
(Photo: L.Friskie)
Resin flow and terpene content

Analysis of resin flow in "resistant" and "susceptible" clones showed that flow over 24 hours differs significantly among different clones, but not between the susceptibility categories. Analysis of resin terpene levels in the phloem showed that the relative levels of delta-3-carene explained over 40 % of the variation in the number of attacks, indicating that clones could be selected for reduced susceptibility on the basis of this monoterpene alone.


(Photo: L.Rocchini)

Association of Rusts and Pitch Moth in the Provenance Trial

A survey of Provenance Trial was carried out in late June when stem rusts were sporulating. Dioryctria cambiicola is the prevalent pitch moth, and Endocronartium harknessii and Cronartium coleosporioides are the prevalent rusts in the Provenance trial. S. novaroensis, C. commandrae, and Atropellis piniphila are also present. D. cambiicola and S. novaroensis were both associated with stalactiform blister rust cankers, and S. novaroensis was also associated with western gall rust on the tree stem.


Rocchini, L.A.,  B.S. Lindgren, and R.G. Bennett. 2000. Effects of resin flow and monoterpene composition on susceptibility of lodgepole pine to attack by the Douglas-fir pitch moth,  Synanthedon novaroensis (Lepidoptera: Sesiidae). J. Appl. Entomol. 124: 87-92.

Rocchini, L.A., K.J. Lewis, B.S. Lindgren, and R.G. Bennett. 1999. Association of pitch moths (Lepidoptera: Sesiidae and Pyralidae) with rust diseases in a
lodgepole pine provenance trial. Can. J. For. Res. 29:1-5

Project funded by Forest Renewal BC and the BC Ministry of Forests

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