Lily Beetles (Lilioceris lilii) are a damaging pest insect for lily (Lilium spp.) growers. The pest chews on the leaves, flowers and stem leaving them looking ragged. If the pest numbers are high enough complete defoliation can occur. Early detection and vigilance are key to managing this pest naturally.
Damage to Plants
Both the larvae and the adults feed on mainly Asiatic lilies and fritillaries. They also feed on Oriental lilies, rubrum lilies, Turk’s cap lilies, native North American lilies, Solomon’s seal, lily-of-the-valley, potato, flowering tobacco, hollyhock, and hosta, but to a lesser degree. The leaves are generally the preferred food, but the stem, buds, flowers and seed pods may also be eaten. Plants will look ragged and chewed on and can be completely defoliated. In the larvae stage the brown fecal shield, the insect covers itself in can be quite unsightly.
Larvae feed exclusively on cultivated and wild lilies (Lilium spp.), Fritillaria spp., Giant Himalayan Lily (Cardiocrinum giganteum) and Canada Mayflower aka False Lily-of-the-valley (Maianthemum canadense) (Kenis M., (2008)). The adults feed on the same hosts as the larvae but may additionally be found feeding on Solomon’s seal, lily-of-the-valley, potato, flowering tobacco, hollyhock, and hosta, but to a lesser degree.
Meet the Pest
Adults: have black heads with big eyes and long black, segmented antennae. The slim thorax and hardened forewings (elytra) are a shiny scarlet red colour, and are quite pitted. The abdomen and legs are black in colour. The overall length of the beetle is approximately 8mm (1/3″).
Larvae: pass through 4 instar stages and size varies according to developmental stage they are at. At maturity they reach about 8-10 mm. They appear as soft brown, squishy masses but the real insect is hidden beneath a fecal shield. The slug-like larvae can vary in colour from red, orange, yellow, green or brown with a black head.
Pupae: are bright orange in colour and encapsulated in a whitish cocoon, constructed from saliva and soil particles and is located in the soil.
Eggs: are laid on the underside of leaves and are about 1-2 mm in length. They are laid in irregular rows of about 2-16 eggs and protected by a thick, sticky brown coating. The eggs start off a baize colour but mature to a reddish orange colour.
Lily beetles over winter as adults in the soil or plant debris, not necessarily near host plants. Adults begin emerging from the soil and leaf litter in very early spring through June. They feed on newly emerging lilies and fritillaria and look for a mate. Once impregnated the females insert their eggs into the underside of lily leaves in rows of 2-16 eggs, using their ovipositor. Egg laying takes place from spring through to late summer, with each female capable of laying several hundred eggs. The eggs begin hatching in about a week (depending on temperatures). The larvae feed and develop through 4 instar stages that takes about 3 weeks. First instars feed on the undersides of the leaves, while 2nd and 3rd feed on whole leaves, beginning at the margins. 4th instars feed on all parts of the plant piling their excrement on top of themselves as camouflage. The larvae are the most damaging stage, capable of stripping a lily plant bare. Once they are fully developed, they return to the soil to pupate. The new adults may begin emerging about 3 weeks later (but this period of diapause can vary by region and may take 2 months) (Kenis M., (2008)). Once they emerge from the soil, they once again begin feeding but do not mate or lay eggs. There is one generation per year (Kenis M., 2008; Childs R., (Updated by: Tawny Simisky on 4/24/2020); Smith T. (updated 07, 2013); Stack P. A., (2009); RHS, (n.d.); Salisbury A., (2008); Mull A., Spears L., (2021)).
Management and Control
- Hand picking the adult beetles or tapping them into a container of warm soapy water works well. They are quick to either fly away or drop to the ground on their backs so that their black undersides camouflage well with the soil. Hold your container under them and give them a gentle tap into the warm soapy water.
- Larvae can be scraped off and destroyed.
- Scout the underside of leaves for egg masses and remove those leaves and destroy.
Plant resistant varieties: such as Lilium henryi ‘Madame Butterfly’, Lilium speciosum ‘Uchida’, and Lilium ‘Black Beauty’ (Robert Childs, Updated by: Tawny Simisky on 4/24/2020).
Biological controls: as a non-native insect there are no natural predators here in North America. However, in Europe there are a few parasitoids that kill the larvae. Research on these parasitoids has been on going and in Canada the parasitic wasp Tetrastichus setifer, has been released in New England, Ottawa and southern Alberta with good results.
- A heavy application of neem oil applied every 5-7 days, will help to control the larvae and may help to deter the adults (Stack P. A., 2009). The young larvae are the most vulnerable to the spray.
- Spinosad (a naturally occurring soil bacterium), applied at regular intervals can be helpful in controlling this pest. Note: this product is currently not available in Canada
- Talcum powder has also had some effect at controlling all stages of this pest (Plantlilies.com, (2007)).
Chemical Pesticides: carbaryl (Sevin) and Malathion (check with your region to see what is legal for you to use).
Updated Jan. 18, 2023
Brown, W.J. 1946. Some new Chrysomelidae, with notes on other species (Coleoptera). Canadian Entomologist Canadian Entomologist 28:47-48 online @ DOI: https://doi.org/10.4039/Ent7847-3
Childs R., (Updated by: Tawny Simisky on 4/24/2020). Lily Leaf Beetle. UMass Extension Landscape, Nursery and Urban Forestry Program. https://ag.umass.edu/landscape/fact-sheets/lily-leaf-beetle
Ernst C., (n.d.). The Lily Leaf Beetle (Lilioceris lilii): an unwelcome invader. https://www.lilies.org/pdfs/lilybeetle.pdf
HDC, RHS, Imperial College London and Rothamsted Research, (2007). Risk Assessment: The effect of the Red Lily. Beetle, Lilioceris lilii (Scop.) on horticulture in the UK: Results of two surveys of professional horticulturalists in the UK. Summary Report
Kenis M., (2008). Lilioceris lilii (lily leaf beetle). CABI Compendium. https://doi.org/10.1079/cabicompendium.30800
Mull A., Spears L., (2021). Lily Leaf Beetle (Lilioceris lilii Scopoli). Utah State University. https://extension.usu.edu/pests/research/lily-leaf-beetle
Olds College, (n.d.). The Lily Beetle. https://www.oldscollege.ca/about/campus/botanic-gardens/central-gardens/taxonomic-collection/the-lily-beetle/index.html
Plantlilies.com, (2007). Pests and Diseases Lily Beetle – ALBERTA. https://plantlilies.com/lily-culture/pests/lily-beetle-alert-alberta.html
RHS, (n.d.). Lily beetle. https://www.rhs.org.uk/biodiversity/lily-beetle
Salisbury A., (2008), THE BIOLOGY OF THE LILY BEETLE, Lilioceris lilii (Scopoli) (COLEOPTERA: CHRYSOMELIDAE). https://www.rhs.org.uk/science/pdf/plant-health/lily-beetle-litrev-pdf.pdf
Smith T. (updated 07, 2013). Extension Greenhouse Crops and Floriculture Program; University of Massachusetts, Amherst. Lily Leaf Beetle. https://ag.umass.edu/greenhouse-floriculture/fact-sheets/lily-leaf-beetle
Stack P. A., (2009); (collaborating researcher, Hampden, Maine; with Professor Eleanor Groden and Extension Professor, Lois Berg Stack), (2009). Bulletin #2450, Lily Leaf Beetle. https://extension.umaine.edu/publications/2450e/
Whitman A., (updated 01/25/2021). Controlling Lily Leaf Beetles. https://www.gardeners.com/how-to/lily-beetle/8090.html
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