Dendrolimus pini
Dendrolimus pini, the pine tree lappet moth or pine moth, is a pest species, a defoliator of coniferous forests. It belongs to the order Lepidoptera and is one of many lappet moths in the Lasiocampidae . First described by Carl Linnaeus in his 10th edition of Systema Naturae, it has a wide geographic range and has since been documented in Europe, Asia, and North Africa. D. pini has a preference for the Scots pine, its main host.
Etymology
Breaking down the scientific name Dendrolimus pini, we find both Greek and Latin roots. The prefix "dendro" is from Greek dendron, "tree". The suffix "limus" is Latin for "mud", which may be a reference to the moth's colouration. The epithet "pini" is Latin for "pine".Description
Eggs
When first laid, the eggs are initially blue-green in colour, but over time they lose their colour, fading into a gray. The eggs are approximately 2 mm in size and take about 14 days to hatch.Larvae
Larvae reach an approximate length of 2-3 inches. The caterpillar's thorax is covered in black hairs and made up of thick alternating steel-blue bands; the abdominal segments have a black mark bordered by irregular white lines. The pupation stage lasts about two weeks. During this time, the larvae create a cocoon, usually attached to branches or crevices in the bark of tree crowns, with varying coloration. These loose, partially transparent cocoons vary from yellow-brown to deep black and are often marked with steel-blue hairs.Adults
Adult D. pini can reach a size of 2 to 3 1/2 inches. Females of this species are generally larger. The typical wingspan of the females ranges between 70–90 mm, while the smaller males' wingspan falls within 50–70 mm. The females are adapted to be laden with eggs and are thought to be used for short distances, whereas the males can disperse several kilometers to facilitate mate-seeking. In addition to being smaller, males of this species are usually darker than females. The forewings of this moth are gray-brown to brown with a lateral band and a non-uniform stripe along the edges. Hind wings are red-brown to gray-brown.Life cycle
Depending on the climate and habitat, the pine moth has a varying growth cycle of one to three years. Swarms begin in July and August, laying their eggs on the host trees. D. pini are capable of dispersing through wind, which may achieve greater distances, or through crawling. Female D. pini lay 150-300 eggs in aggregations of up to 100 eggs. Eggs are most often laid on the needles of P. sylvestris, but also on branches and trunks. Once hatched, the larvae first feed on egg shells before seeking uninfested trees to consume the bark of young shoots or up to 1000 needles each. Come October and November, the larvae stop feeding and move to the tree litter, where they remain over the winter. After snowmelt, around February to March, the larvae climb the trees again and feed on the tree crowns, resulting in mass defoliation. Pupation occurs by late May or early June, and adults emerge after about four weeks. Adult D. pini do not feed, which allows them to live for approximately 9 to 10 days. From larvae to adult moth, D. pini undergoes up to an estimated eight instars, which is dependent on the conditions during larval development. Due to the sex size difference, female D. pini moths undergo more instars than the males. In warmer climates, D. pini has a single generation per year, whereas in cooler regions, the larvae overwinter twice, resulting in a development period of approximately two years.Predators
Like most moths, some of the primary predators are bird species. The cuckoo, golden oriole, starling, coal-tit, jay, thrush, rook, jackdaw, chaffinch, and woodpecker are most common. In addition to birds, some mammal species, bats, and moles, and insect parasitoids are also primary predators. Bird and mammal predators can target both the larval and adult stages.Diet
While D. pini is considered oligophagous with a preferred and primary host of Pinus sylvestris ''D. pini is adaptable to other European and North American pine species, or to trees with two to three needle fascicles. Research has examined the extent of this diet to assess the risk potential this moth poses. It was found that feeding on tree species similar to their host resulted in little mortality in the experimental context, where growth, development, and morphological parameters were most optimal when D. pini fed on American pine species and pine species with three needles in a fascicle. D. pini were less capable of adapting to Five-needle . and experienced clogged digestive systems if fed with dry needles or leaf tissues. D.pini attacks healthy forests that are over 60 years old.Tree species that D. pini can develop fully on are: