Pine needle sheathminer, Zelleria haimbachi
   

Fig. 24   Pine needle sheathminer larvae are relatively small and tan-coloured.	Fig. 25  Fading of current year's foliage due to attack by pine needle sheathminer.	Fig. 26  Frass, webbing, and necrotic needles resulting from attack by pine needle sheathminer.

Distribution:  Throughout southern B.C.

Tree Species Attacked: Lodgepole pine, ponderosa pine, and occasionally white pine are attacked. It is found mostly in juvenile stands.

Insect Description & Damage Symptoms:  Immature larvae are about 0.2 cm long and reach 1.4 cm prior to pupation. Larvae are tan-coloured with two dull-orange stripes running lengthwise along the back. The colour changes to a greenish hue before pupation. Brown pupae can be found in the mass of silken webbing around the needle bases in early summer.

On damaged trees, the current year's foliage appears faded and needles may be shorter than normal. Some needles may droop back, or hook, towards the needle base. A small hole may be noted in the sheath surrounding an attacked fascicle. By late summer, damaged needles are shed and commonly accumulate in webs along the main stem. Feeding occurs throughout the growing season.

Damage:  Attacks usually occur in juvenile to immature pine stands. Damage is restricted to the current year's foliage, but up to 100% of the new growth may be destroyed over hundreds of hectares. The extent of defoliation varies among trees within an attacked stand, and some trees may escape attack entirely. Tree mortality has not been associated with this insect. However, growth reduction resulting from defoliation has been documented in ponderosa pine plantations.

Similar Damage:  Damage may be confused with pine needle cast disease. Sheaths mined by the sheathminer are distinctive in that they result in needles being easily pulled out, leaving the sheath attached to the twig. Needle cast disease results in shedding of needles complete with the sheath. Needles affected by Lophodermella shed the previous year's needles in the summer, while the pine needle sheathminer affects the new year's growth.

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BC Ministry of Forests
Forest Practices Branch
P.O. Box 9513 Stn. Prov. Gov.
Victoria, BC
V8W 9C2

Section phone: (250) 387-8739
Section fax: (250) 387-2136

Last updated March 04, 2002