Most Common Alfalfa Plant Pests:
Identification and Treatment Guide

Alfalfa, a versatile and nutritious crop commonly used for animal feed, is susceptible to a variety of pests that can significantly impact yield and quality. Proper identification of these pests and timely treatment are essential to protect alfalfa crops from damage. In this article, we will discuss some of the most common alfalfa plant pests, their identification characteristics, and effective treatment strategies.

Alfalfa Weevil (Hypera postica)

Identification: The alfalfa weevil is a small, greenish-brown insect with a distinctive dark stripe down its back. Adult weevils are about 1/4 inch long and have a snout-like extension on their heads. Larvae are yellow-green with a black head and consume alfalfa foliage, causing skeletonization of leaves.

Treatment: Cultural practices such as timely cutting can help control alfalfa weevil populations. Insecticidal sprays may also be applied if the infestation reaches economic thresholds.

Aphids

Identification: Aphids are small, soft-bodied insects that come in various colors such as green, black, or pink. They feed on sap from alfalfa plants, causing stunted growth and yellowing of leaves.

Treatment: Natural predators like ladybugs and lacewings can help control aphid populations. Additionally, insecticidal soaps or neem oil can be used for chemical control.

Cutworms

Identification: Cutworms are nocturnal caterpillars that feed on young alfalfa plants, cutting them off at the base. They are typically brown or gray in color and curl up when disturbed.

Treatment: Bacillus thuringiensis (Bt) products are effective against cutworms. Physical barriers like collars around plant stems can also prevent cutworm damage.

Spider Mites

Identification: Spider mites are tiny arachnids that suck sap from alfalfa plants, causing stippling on leaves and webbing on the undersides. They thrive in hot, dry conditions.

Treatment: Spraying affected plants with water can help reduce spider mite populations. Insecticidal oils or miticides may be used for severe infestations.

Leafhoppers

Identification: Leafhoppers are small insects that feed on alfalfa sap, causing yellowing and browning of leaves. They are quick-moving and may jump when disturbed.

Treatment: Insecticides targeting leafhoppers can be used if populations exceed threshold levels. Planting resistant alfalfa varieties is also a preventive measure.

Root Maggots

Identification: Root maggots are the larvae of certain fly species that feed on alfalfa roots, causing wilting and yellowing of plants. Adult flies lay eggs near plant roots.

Treatment: Biological control using parasitic nematodes can help manage root maggot infestations. Crop rotation with non-host plants is another effective strategy.

Grasshoppers

Identification: Grasshoppers are large insects with powerful hind legs for jumping. They feed on alfalfa foliage, causing extensive defoliation.

Treatment: Biological control methods like introducing grasshopper-specific pathogens or predators can help manage grasshopper populations. Chemical insecticides may also be used as a last resort.

In conclusion, identifying common alfalfa plant pests and implementing appropriate treatment measures are crucial for maintaining healthy crop yields. Integrated pest management practices that combine cultural, biological, and chemical control methods can effectively mitigate pest damage while minimizing environmental impact. By staying vigilant and proactive in pest monitoring and management, alfalfa growers can protect their crops and ensure successful harvests.