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Trouble with bulbs and lily leaf beetle

During garden talks last weekend the most-asked question was about the bulbs that have popped up prematurely during mild weather in December and January. Did the severe cold in early February – when temps dropped suddenly to 0 degrees and below – wreck them? Will we have the first spring flowers?

The answer is good news: The future flowers and leaves weren’t wrecked. Bulbs respond to temperature cues and emerge when they sense warmth. But when the cold resumes, they simply stop growing. The cells contain a kind of antifreeze that prevents the cell walls from splitting and the plant from dying. Once flowers have opened, a sudden freeze damages the petals. In that case you might try covering them the night before the freeze, or sprinkle water on them early in the morning after the freeze. (Freeze damage happens in the morning when ice crystals break up too fast in response to morning sunshine; the water slows that process.) The alternative: Cut the flowers before a freeze and enjoy them indoors.

Lilies in danger

A serious pest of Lilium – true lilies – has arrived in parts of Western New York. It came to Canada from Europe and was discovered in the United States in 1992 in Massachusetts. It’s been spreading ever since. It affects lilies – not daylilies (Hemerocallis). The larvae and adult eat leaves and buds, typically together on the plant, and often leave only bare stems behind. Occasionally they dine relatively lightly on some hostas, hollyhocks, potatoes and Solomon’s seal, but lilies are the species that are truly threatened.

You will recognize these beetles when you see them. They are bright red, about ½-inch long, with black legs, head, and antennae. They feed on the lily foliage as soon as it emerges, seek mates, and lay eggs on the undersides of the leaves. Look for tan-colored lines; the eggs turn orange-red just before they hatch. Sluglike larvae then feed on the leaves – rather disgusting little creatures that pile their excrement on their backs. After feeding for about 20 days they drop to the soil and pupate. Pupae are florescent orange. In about 20 days, adult beetles emerge and also begin eating the lilies. They over-winter in soil or plant debris, not necessarily near the garden since they are strong fliers.

Knowing this cycle can help you manage them, at least if you have only a few lilies. Patrol the garden early in the season. Handpick the adults, squish the eggs and later the larvae. Some pesticides have been labeled for lily leaf beetle but in my opinion their environmental cost is worse than losing the lilies. The ingredient Imidacloprid is one of the causes of bee decline and should never be used near flowers or where bees are active. (See Purdue University’s “Protecting Bees from Pesticides” to help your decision making.)

Biological controls are promising though. In Europe some parasitoid wasps manage this pest. Many have been released in New England, and found far from the release site; beetle counts are diminishing. For more info, trust agriculture college sources in New England, or monitor the Cornell pest management website: or

As this insect is becoming more familiar, I say don’t hesitate to grow some lilies. Just don’t plant thousands.

Other bulbs, other troubles

Spring-flowering bulbs tend to be easy to grow and trouble-free, except for animal damage. If you have deer and rabbits in your yard, daffodils and alliums would be your easiest choice. Snowdrops (Galanthus nivalis), among the first flowers of spring, are rarely nibbled. Like daffodils and alliums, they also multiply so they are a bargain in the right place. Chionodoxa (Glory-of-the-snow), hyacinths, and Scilla siberica (Siberian squill) are also critter-resistant. Crocuses are rarely touched by deer, but rabbits definitely eat them. Fritillaria are not eaten by animals, and have the added advantage of smelling badly and possibly driving mammals away from the whole bed.

Blocking and deterring critters are the primary methods of handling the animal problem. Deer fencing may be viable but at some point one questions whether the results are worth the effort or the generally unattractive appearance. I think chicken wire is the most useful product for deterring animals. Try it as a tunnel or cage over some bulb beds, to protect them until it’s time to enjoy the flowers. (Yes, I know, sometimes the flowers are then eaten overnight once you remove the cage – but it depends upon your animal population.) You can also make an underground cage to keep squirrels from removing and replanting your bulbs. Old window screens laid on the ground can prevent squirrels from digging up the bulbs between planting time (fall) and emergence in spring.

Commercial deterrent products work if you persist with them. Some cling to the plant in the rain, but most need multiple applications. I believe they are worth the price. Having tried many, I can’t swear which are best; just keep sprinkling. Homemade repellents include egg mixtures, garlic, animal hair, Irish soap (probably other strong-scented soaps) and pepper. I do not recommend cayenne pepper because it can cause squirrels great pain or eye damage.

If you must have tulips or lilies – the most delicious bulb plants for animals – the prettiest protective measure is surrounding them with repelling, undesirable plants. Plant lots of daffodils or alliums around your clump of tulips. Animal-proof plants include astilbes, ferns, bee-balm, grasses, lavender, Russian sage and many herbs.

Or you could scare the animals away. Radios and lights going on and off work for a while. Deer are xenophobic; they dislike anything new – but they learn. A dog around the yard, if you can provide a suitable fence or enclosed deck, scares them. Deer often figure out where the dog’s fence is, but your pet certainly holds them back. (Consider pet adoption as one of the joys of life, but do so only if you can make a permanent commitment.)

While I have discussed problems with bulbs, do not be misled: Bulbs are among the easiest and most satisfying flowering plants you can grow. And they’re popping up any day now.

Sally Cunningham is a garden writer, lecturer and consultant.