If you spotted a bright red beetle in your Michigan garden, the most likely culprit is one of four species: the invasive scarlet lily beetle, the native red milkweed beetle, the red turnip beetle, or a ladybug variant. Telling them apart is straightforward once you know what plant it was sitting on and whether it has spots.
The Scarlet Lily Beetle
This is the red beetle generating the most concern in Michigan right now. The scarlet lily beetle is an invasive pest from Europe and Asia that arrived in North America on imported lily bulbs, first showing up in Montreal in 1945, reaching the United States in 1992, and confirmed in Michigan by 2016. It has been spreading across the state ever since.
The beetle is solid bright red with no spots, about a quarter inch long, with a black head and a longer, oval-shaped body. If it’s sitting on a lily or fritillary plant, that combination of features is almost a guaranteed identification. It does not have the dome shape of a ladybug or the long antennae of a milkweed beetle.
Both the adults and larvae chew irregular holes in lily leaves, stems, and developing buds, but the larvae do the real damage. In heavy infestations, they can completely strip a plant of its leaves and destroy every flower. The larvae themselves are easy to overlook because they cover themselves in their own excrement as a defense tactic, making them look like small, slimy greenish-brown slugs or tiny piles of animal droppings on the leaf surface.
The beetles target true lilies, including tiger lilies, Easter lilies, Asiatic and oriental hybrids, and fritillaries. They can also cause minor damage to lily of the valley, Solomon’s seal, potatoes, hollyhocks, and hostas. Daylilies, canna lilies, and calla lilies are not attacked, despite having “lily” in their names.
Managing Lily Beetles in Your Garden
Hand-picking adults off your plants is effective if you stay on top of it, especially in spring when the overwintered beetles first emerge and are easy to spot against green foliage. Drop them into a container of soapy water. The challenge is that hand-picking and insecticide sprays both need to be repeated every year and can harm beneficial insects in the process.
Michigan State University Extension has launched a biological control program using three species of tiny parasitoid wasps from the lily beetle’s native range in Europe. Female wasps lay their eggs inside beetle larvae, and the developing wasps consume the larvae from within, preventing the next generation of beetles. This approach targets only the lily beetle without the collateral damage of broad-spectrum sprays. The program is still expanding, so reporting lily beetle sightings helps researchers track where to focus releases.
If you find scarlet lily beetles, you can report them to the Michigan Department of Agriculture and Rural Development by emailing MDARD-InvasiveSpecies@michigan.gov or calling 1-800-292-3939. A clear photo showing the beetle’s color, body shape, and the plant it was on is the most useful thing you can submit.
Red Milkweed Beetle
The red milkweed beetle is a native Michigan insect that looks superficially similar to the lily beetle but is easy to distinguish. It is reddish-orange with black spots scattered across its wing covers and has dramatically long antennae, much longer than anything you’d see on a lily beetle. It belongs to the longhorn beetle family, and its larvae bore into milkweed roots.
You will almost exclusively find this beetle on common milkweed plants. Like monarch butterflies and other milkweed specialists, it absorbs toxins from the plant that make it unpalatable to predators, which is why it sits out in the open without much concern. This beetle is harmless to gardens and beneficial to the ecosystem. If you’re growing milkweed for monarchs, seeing red milkweed beetles is a sign your patch is thriving.
Red Turnip Beetle
The red turnip beetle is about 7 mm long with a bright red body and three distinct black stripes running lengthwise down its back. Its head has a mix of red and black markings. It feeds on plants in the mustard family: turnip, radish, canola, rapeseed, and other brassicas.
Damage from this beetle typically starts at the edges of a field or garden bed and moves inward. Light infestations leave partial holes in leaves, but heavy populations can defoliate and kill entire plants by feeding on leaves, flowers, stems, and seedpods. If you’re growing brassica crops and find red beetles with black back stripes, this is your species.
Ladybugs and Asian Lady Beetles
Red, dome-shaped beetles with spots are some form of ladybug, but the species matters. Michigan has both native ladybugs and the invasive Asian lady beetle, and the two behave very differently.
The Asian lady beetle is the one that swarms the sides of houses every fall, packing into wall spaces, attics, and window frames looking for a warm place to spend winter. Its color ranges from pale yellow to deep red, and it can have anywhere from zero to 22 spots. The best identification feature is a black “M” or “W” shape on the white plate just behind its head. Its body tends to look puffy or bulbous compared to native species.
The native convergent lady beetle is slightly smaller and more elongated. It has two thin white diagonal lines on a black background behind its head that angle toward each other (hence “convergent”). Spot count varies from none to more than a dozen. Native ladybugs overwinter outdoors in natural shelters rather than inside buildings. Both species eat aphids and other garden pests, so neither causes plant damage, but the Asian lady beetle’s habit of invading homes in large numbers makes it a nuisance.
Quick Identification by Plant
The fastest way to identify a red beetle in Michigan is to note what plant it was on:
- On lilies or fritillaries: solid red, no spots, black head. That’s the invasive scarlet lily beetle.
- On milkweed: reddish-orange with black spots and long antennae. That’s the native red milkweed beetle.
- On turnips, radishes, or canola: red with three black stripes on its back. That’s the red turnip beetle.
- On roses, vegetables, or just about anywhere: dome-shaped with spots. That’s a ladybug or Asian lady beetle.
If the beetle is solid red with no spots and you found it on a lily, take a photo and check the undersides of nearby leaves for larvae disguised in dark, slimy excrement. Catching an infestation early, before larvae strip the plant, gives you the best chance of saving your lilies.