Fir Coneworm: Appearance, Territory, Damage and Life Cycle

Latin name: Dioryctria Abietivorella

Appearances: Description of the pest and its effects Coneworms are mottled grey snout moths with minor colour bands as adults. Coneworm larvae are small, cream-colored or light brown in tone with a dark head. Coneworms prey on the fragile bark tissues of genuine firs by burrowing into shoot tips or stems, especially around wounds. The wingspan is between 10 and 13 mm. The forewings are mostly black and white, with a large mark in the middle.

Host plants: Balsam fir, black spruce, eastern white pine, jack pine, Norway spruce, red pine, red spruce, scots pine, and white spruce are the main hosts.

Territory: The fir Coneworm, Dioryctria Abietivorella, is a snout moth species in the Dioryctria genus. Augustus Radcliffe Grote first described it in 1878, and it can be found throughout North America, from southern Canada south to California in the west and North Carolina in the east.

Damage Caused: Cones bound together by frass mixed with webbing, chewed needles, and mined terminal shoots are all signs of an infestation. Larvae like cones, although they’ll eat terminal shoots, trunk bark, and huge limbs as well. The larvae will occasionally mine the tree’s actual branches or trunk. A pitch heap near an entry point on the trunk of young pines reveals the species’ existence. The fir coneworm does not harm the tree, but it can wipe out an entire seed and cone crop in severe infestations. It is very harmful in seed orchards.

Life Cycle and Habits: In general, one generation occurs per year, but the life cycle is quite varied. Adults that have just emerged begin flying in late spring, and adults are present and active well into the summer.

In wild populations, no eggs have been discovered. Eggs are deposited singly on bark or other surfaces in laboratory populations. Mature fifth-instar larvae exit the cones in late summer and early fall to pupate, most likely in the duff layer (adults have been reared from soil beneath infested trees). Late-season adult larvae hibernate in hibernacula until the spring and early summer, when they pupate. The egg is oval in shape (0.5 mm x 0.7 mm) and pale green-white when young, turning orange as it matures. LARVAE: Young larvae have brown head capsules and amber bodies; adult larvae have darker brown bodies with faint longitudinal stripes (18-20 mm long) and rows of dorso-lateral dots. Pupae are reddish-brown in colour and are about 11 mm in length. ADULT: Medium-sized moth (wingspan 25-28 mm); forewings narrow, grey, with transverse lighter bars bordered by black (forming a conspicuous “w” mark towards the wing tip); hindwings lighter, unmarked.