Pine needle sheathminer
Quebec, New Brunswick, Ontario, British Columbia
Damage, symptoms and biologyThe pine needle sheathminer can cause near total defoliation during outbreaks. Infestations were recorded in Penticton in 1951; Spences Bridge in 1958; Louis Creek and Scotch Creek in 1962; Clearwater-Vavenby 1979-80; Clearwater-Shuswap 1985-92. Mortality has not been observed but tree growth may be reduced.
Mature larva up to 14 mm long. Head, small tan. Body, slender, greyish with broad, dull orange lateral stripe along the length of the body. Shortly before pupation the larva takes on a green colour.
The sheathminer overwinters as a first instar larva mined into a needle. In the spring the larva becomes active and lengthens the mine to about 5 mm. At this time, the larva bores to the surface, leaves the mined needle and migrates to the new growth flush where it begins feeding within the sheaths of the young needles. Typically each larva will feed on 6-10 fascicles of needles before pupating. Pupation occurs in late June in an elongated white cocoon between the bases of the mined needle sheaths and lasts about 10 days. Adults emerge in July. Females lay eggs singly from early July to mid-August, preferring current year foliage. The eggs hatch in about 10 days and the larvae bore directly down through the bottom of the egg and into a needle.
Canadian Forest Service Publications
Diet and feeding behaviour
: Feeds on the leaves of plants.
- Miner: Feeds inside the blade of a leaf, between the epidermal layers, or beneath the bark of plants, by first excavating a mine into these tissues.
Information on host(s)
The principal host of the pine needle sheathminer is lodgepole pine; other hosts include ponderosa pine and jack pine.