Lupine plants, with their distinctive tall spires of pea-like flowers, are popular additions to many gardens, offering color and vertical interest. Gardeners cultivate them for their beauty and ability to attract pollinators. However, lupines can become a food source for various creatures. Understanding which pests and animals target these plants is the first step in protecting them.
Common Insect Pests of Lupines
Lupines are susceptible to several common insect pests that can cause noticeable damage. Aphids, particularly the lupine aphid, are small, pear-shaped insects that cluster on stems and leaf undersides. These sap-sucking insects cause stunted growth, distorted foliage, and a sticky honeydew residue that attracts sooty mold. Heavy infestations can significantly weaken the plant.
Slugs and snails are also common culprits, especially for young lupine plants. They feed on leaves, creating irregular holes and ragged edges, and often leave behind a silvery slime trail. Young seedlings can be entirely consumed. These mollusks are active in moist conditions and at night, so their damage is often visible before the pests themselves.
Caterpillars, the larval stage of moths and butterflies, can also defoliate lupines. Cutworms chew through stems at the soil level, severing young plants. Other caterpillars feed on leaves and stems, or bore into pods to consume seeds. Severe attacks can skeletonize leaves, impairing photosynthesis. Weevils, including the lupine-root weevil, can also affect lupines, with adults notching leaf edges and larvae damaging root nodules.
Mammals That Graze on Lupines
Larger animals can also pose a threat to lupine plants. Deer generally find lupines less appealing due to bitter and potentially toxic alkaloids. While often labeled “deer-resistant,” deer may still browse them during food scarcity, causing ragged or torn plant parts. This damage occurs because deer lack upper incisors and tend to pull and chew rather than make clean cuts.
Rabbits are another common garden mammal that can graze on lupines. Despite some reports of toxicity, rabbits, particularly Eastern Cottontail Rabbits, may still eat lupine seedlings and young plants, especially when other food is scarce. Their browsing results in cleanly bitten stems or leaves, as rabbits have sharp incisors. Voles and groundhogs can also consume lupines, often targeting roots or entire young plants.
Identifying Damage and Culprits
Accurately identifying the source of damage is key to protecting lupines. Regular inspection helps detect pest activity early. Examine leaves for irregular holes, ragged edges, or a skeletonized appearance, which are common signs of feeding by slugs, snails, or caterpillars. The presence of shiny, sticky residue on leaves or stems suggests an aphid infestation, often accompanied by visible clusters of the small insects.
Look closely at the plant’s stems for signs of chewing or wilting, which could indicate cutworms or stalk borers, particularly on younger plants. If entire plant parts are missing or stems are cleanly bitten off, larger animals like rabbits are likely responsible. Conversely, torn or shredded foliage points more towards deer browsing. Checking the soil around the plant for slime trails indicates slug or snail activity. Observing plants at different times of day, especially at dusk or dawn, can also help catch nocturnal feeders in action.
Protecting Your Lupine Plants
Protecting lupine plants from pests and grazing animals involves preventative measures and targeted interventions. Cultural practices, such as proper plant spacing for good air circulation and avoiding over-fertilization, can reduce aphid attraction. Watering plants in the morning allows foliage to dry before evening, deterring slugs and snails that thrive in moist conditions. Removing plant debris in the fall eliminates overwintering sites for pests.
Physical barriers offer a direct line of defense. For slugs and snails, copper tape or a scattering of gravel, crushed shells, or diatomaceous earth can create an abrasive barrier. Netting or fencing can deter larger animals like rabbits and deer, especially for young plants. Manual removal of slugs, snails, and visible caterpillars is effective if done regularly, particularly at night.
Organic deterrents and treatments provide environmentally friendly solutions. A strong spray of water can dislodge aphids. Insecticidal soaps, neem oil, or garlic-based sprays control aphid populations. Introducing beneficial insects like ladybugs and lacewings, or planting companion plants such as dill, yarrow, or marigolds, attracts natural predators that help control aphids. For root-damaging pests like weevil larvae, applying beneficial nematodes to the soil can be an effective biological control.