Coniferous forests (also referred to as taiga, the Russian word for coniferous forests) consist primarily of conifers, which are plants that bear cones and needles rather than regular flat leaves. These forests form a band around the northern portions of North America and Eurasia, just above deciduous forest regions and just below tundra regions. Three of the most well-known--and most destructive--coniferous forest insects are the spruce budworm, the western conifer seed bug and the Siberian coniferous silk moth.
The spruce budworm (Choristoneura fumiferana) is actually a type of moth; however, its larva or caterpillar-form is much more infamous in coniferous forest regions. According to the United States Department of Agriculture (USDA), these caterpillars are incredibly small and bore into the buds and needles of conifers to feed. These feeding habits can have terrible effects on trees, and typically result in the needles turning brown and falling off as if they have been burnt. Spruce budworms occur most commonly in the Northeastern United States and Canada, but range as far west as Montana. The budworms like to feed on black, red and white spruce trees, as well as pines, hemlocks and tamaracks. However, according to the USDA, they cause the most devastation to balsam firs in the United States. While the caterpillars of the spruce budworm start out a light yellowish-green colour, they eventually grow darker and end up brown. The moths are typically reddish-brown and have grey markings.
Western Conifer Seed Bug
According to the University of Rhode Island, western conifer seed bugs (Leptoglossus occidentalis) are native to the west coast of the United States, and began spreading east during the 1960s (they reached the Northeastern U.S. in the 1990s). The winged bugs are members of the Coreidae insect family, and are well-known for having flat, leaflike growths on their back legs. They are typically a dull brown colour, and have white zigzag patterns on their backs. According to the USDA, western conifer seed bugs feed on the cones of conifers using a specialised mouthpart, which can pierce the cones' scales, allowing the bugs to suck out the pulp. The bugs are particularly fond of hemlocks, Douglas firs and white spruces as well as red, white, mugo, Austrian and Scots pines.
Siberian Coniferous Silk Moth
The Siberian coniferous silk moth (Dendrolimus sibiricus) is found across the Asian continent, including the countries of Russia, China, Kazakhstan, Mongolia, North Korea, South Korea and Japan. According to the Canadian Food Inspection Agency, the moth caterpillars are known for feeding on conifer needles and may also consume the bark off cones and young shoots. Some of the common genera of conifers on which they feed include tsuga, pinus, picea, larix and abies. While the caterpillars of the Siberian coniferous silk moth are dark brown or black and feature numerous hairs and spots, the moths range from light grey or brown to dark brown or black. The moth's front wings typically feature two dark bands and centralised white spots.
- Canadian Food Inspection Agency: Dendrolimus sibiricus (Tschetverikov) - Siberian coniferous silk moth
- Forest Insect & Disease: Leaflet 160: U.S. Department of Agriculture Forest Service: Spruce Budworm in the Eastern United States
- University of Rhode Island Landscape Horticulture Program: Western Conifer Seed Bug