Garden Pests: Those Dreaded Red Lily Leaf Beetles

When I saw my first red lily leaf beetle (RLLB),  Lilioceris lilii, in 2006, I had no idea how much devastation they would ultimately wreak in my garden. Without toxic chemicals, it is very difficult to keep them in check, and since we pride ourselves on not using chemical pesticides in our gardens, it sometimes seems as if we have been fighting a losing battle. [Read more about our methods HERE.]

The RLLB is an oval beetle with bright red elytra and hindwings. You can't mistake it for the sweet and helpful lady bug. Lady bugs are smaller, rounder, spotted, and have a larger head in proportion to the body than the RLLB.

The lady bug (L) should not be confused with the Red Lily Leaf  Beetle (R)

The RLLB has a special fondness for Asiatic lilies and fritilaria, so much so, that I have dug up most of ours and relegated the remains of them to the compost pile.

Once one of my favorite flowers, we had Asiatics covering the entire middle of the island that surrounds our mailbox and interspersed them with the daylilies as well.

But when lilies aren't around, contrary to popular opinion, the RLLB's will attack other plants and I have found them munching away on daylilies (which are not true lilies and are not usually one of their favored plants to attack), peonies, phlox, and roses.

I usually try to stay ahead of them with aggressive spraying beginning in April, but with so much rain this spring, that didn't happen and we are now paying the price for that. Since we have only a few lilies remaining, for the first time ever, this spring I was dismayed to find them attacking one of our clematis.

An unpleasant find: red lily leaf beetles on our Sweet Autumn clematis

The most eco-safe method we've come up with to deal with these pests is frequent spraying with Neem and also spraying the soil around the plants with a 10% solution of ammonia. The ammonia kills larvae that may have fallen down onto the soil. Some of the Bayer products reportedly kill RLLB's on contact, but I have not found that to be the case. And since the pesticides in the Bayer products are toxic to fish, we can't use them here in any event.

One key to successful spraying is to spray under as well as on top of the leaves. The RLLB deposits its eggs on the under side of the leaves where they hatch into voraciously hungry larva that escape notice because they cover themselves with dung.

Not only do the larvae do more outright damage to the plants than the adult beetles, if you don't adequately deal with them, you'll be dealing with more of these little nasties in short order. First they'll eat until they defoliate your lily and then they'll lay more eggs and well... the process continues. Relentlessly. But be sure to use Neem either early in the morning or later in the evening, before or after the bees will be out collecting pollen and nectar as it is toxic to bees..

I mix the Neem according to the directions on the container and then add 1/4 cup of canola oil and 3 Tablespoons of clear dish soap (like Seventh Generation) per half gallon. I rarely need more than a half gallon of spray at a time, since our lily collection is all but gone at this point, but I spray everything around the lilies, since my experience is that these hungry horrors will eat anything and everything if the lilies aren't readily available.

One final note:  Picking them off the plant and killing them is easier said than done. When you attempt to pick them off, they curl up reflexively and drop onto the ground under the plant, back side down with their black belly facing up making them impossible to see. I've had a bit of luck sliding a sheet of white paper on the ground under the plant with sticky tape attached to it (sticky side up) or even smeared with petroleum gel or thick shampoo. (The cardboard from pantyhose works well for this). Shake the leaf or knock them off with a stick or tweezers and they get stuck in the petrolatum or tape. Fold the mess up into a plastic garbage bag and you're done.