Red lily beetle, Lily leaf beetle
The scarlet lily beetle, red lily beetle, or lily leaf beetle (Lilioceris lilii), is a leaf beetle that eats the leaves, stem, buds, and flowers, of lilies, fritillaries and other members of the family Liliaceae. It lays its eggs most often on Lilium and Fritillaria species. In the absence of Lilium and Fritillaria species, there are fewer eggs laid and the survival rate of eggs and larvae is reduced. It is now a pest in most temperate climates where lilies are cultivated.
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TerrestrialTerrestrial animals are animals that live predominantly or entirely on land (e.g., cats, ants, snails), as compared with aquatic animals, which liv...
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OviparousOviparous animals are female animals that lay their eggs, with little or no other embryonic development within the mother. This is the reproductive...
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starts withThis lily beetle belongs to the order Coleoptera, and the family Chrysomelidae, the leaf beetles. The adult lily beetle is about 6 to 9 mm (¼–⅜ in) in length, with relatively long legs and antennae. Its elytra (harder forewings) are bright scarlet and shiny. Its underside, legs, eyes, antennae and head are all black. It has large eyes, a slim thorax, and a wide abdomen. Each antenna is made up of 11 segments. The eyes are notched and there are two grooves on the thorax.
This lily beetle may be confused with the cardinal beetle (Pyrochroa serraticornis), which also has red elytra and a black underside. The wing cases of the lily leaf beetle are dimpled and are shinier and more rounded than those of the cardinal beetle, which are relatively dull, and narrower, flatter, and more elongated. The cardinal beetle also has comb-like antennae. The lily leaf beetle is herbivorous, while the cardinal beetle preys on insects. The lily leaf beetle is also confused with unspotted ladybirds, but it is narrower in shape.
The lily leaf beetle is indigenous to parts of Europe and Asia. It is thought to have been introduced to North America through the importation of plant bulbs in 1943. First spotted in Montreal, it spread throughout Canada and appeared in Massachusetts in 1992, and by 2012 was in all six New England States, as well as New York and Washington states. In Canada it is found from the Maritime Provinces west to Manitoba. As of 2001, it spread as far west as Alberta, and as of 2017 full infestations reported as far north as the Edmonton, AB area. It has also become established as an invasive species in the United Kingdom since being first recorded in 1839, although the first colony did not become established until 1939 and it did not spread far until the 1980s, then more rapidly from the 1980s. Since then it has spread from Surrey in southern England as far north as Inverness, Scotland. It is also found in Ireland. It is also found in the Middle East and North Africa.
Often the first evidence of lily leaf beetle infestation is sticky brown frass piles containing larvae on leaves. The larvae remain in the frass for protection from the sun and predators. However, the fecal shield is not effective protection against parasitoids, and it may actually make it easier for parasitoids such as the wasp Lemophagus pulcher to locate the larvae.
An adult that senses danger displays a defense mechanism, thanatosis, becoming motionless, folding up its appendages and falling with its black under surface facing up, thereby helping it camouflage with the ground to get away. If unable to escape, they are also able to ‘squeak’, by rubbing two parts of their body together, which may be used to startle the attacker. This process is known as stridulation and could even shock a bird or any other predator that may attack the lily leaf beetle.
Lilies may first show evidence of holes chewed in the leaves from consumption, and if left unchecked rapidly progress to blackening, and total loss of the leaves, leaving only the stem. Beetles and their larvae may also inhabit and devour the developing flower buds. Invasion may occur shortly after the new plants emerge from the soil, particularly if there are nearby Fritillaria which emerge earlier than Lilium. While Lilium and Fritillaria are affected, Hemerocallis is not. All types of lily may be affected, but while Asiatic lilies are the most vulnerable, some Oriental lilies may be more resistant. Resistant types include Lilium henryi 'Madame Butterfly', Lilium speciosum 'Uchida', and Lilium 'Black Beauty'. Other garden plants affected include Convallaria majalis, Polygonatum, potato (Solanum tuberosum), flowering tobacco (Nicotiana), hollyhock (Alcea) and Hosta.
The beetle overwinters in the soil and emerges early in spring. The adult is generally found in moist, cool environments. It emerges in spring to feed and mate. The female can lay up to 450 eggs each season in batches of about 12 on the undersides of leaves. It arranges the red-orange to brown eggs in narrow irregular lines along the midrib, where they are more concealed. The eggs then hatch into yellow, brown or orange larvae in about 1–2 weeks.
The larvae feed for up to 24 days, beginning underneath the leaf then working up the rest of the plant, and cause the most damage. Their preferred feeding locale is underneath the leaf or at the node where the leaf meets the stem. They then burrow in the ground to pupate in a cocoon of soil bound with saliva. In about 20 days they emerge as adults and continue to feed until winter. More than one cycle can occur in one year.
