More Pesky Tomato Pests

Controlling Hornworm and Other Tomato Pests in Your Garden

Summer is the season of tomatoes, a time when gardeners eagerly anticipate harvesting their vibrant red, yellow, rainbow, or green fruits. However, as tomato plants flourish, they often attract a variety of pests eager to feast on their leaves and fruits. From the notorious tomato hornworm to lesser-known invaders, these pests can cause significant damage if left unchecked. Here’s an in-depth guide to identifying and managing common tomato pests, ensuring your garden thrives throughout the growing season.

The Infamous Tomato Hornworm

The tomato hornworm is one of the most recognizable pests in a tomato garden. These large, green caterpillars blend seamlessly with the plant foliage, making them difficult to spot. Their voracious appetite can defoliate a plant quickly, leaving behind damaged leaves and fruit. Handpicking hornworms off plants is an effective method, but for larger infestations, using organic insecticides containing Bacillus thuringiensis (Bt) is recommended. Bt targets caterpillars specifically, protecting your tomatoes without harming beneficial insects.

Other Tomato Pests to Watch

While hornworms often steal the spotlight, many other pests pose threats to your tomato plants.

1. Beet Armyworm

Spodoptera exigua, commonly known as the beet armyworm, is a formidable foe for tomato plants in certain regions. Female moths lay egg clusters, and the hatching larvae begin feeding on leaves near the cluster. As they grow, they migrate, attacking leaves and fruit. To manage beet armyworms effectively:

• Use products containing spinosad or Bacillus thuringiensis (Bt).
• Apply treatments in the evening when the larvae are most active.

2. Flea Beetles

Epitrix hirtipennis, or flea beetles, are small but damaging pests that primarily target tomato seedlings.

• Adult Flea Beetles: Chew tiny holes in leaves, creating a characteristic “shotgun” appearance.
• Larvae: Damage the underside of leaves and roots.

Young plants are particularly vulnerable, as a high flea beetle population can wipe them out. To manage these pests:

• Use row covers to protect seedlings.
• Apply organic insecticides labeled for flea beetles, such as neem oil or pyrethrin.

3. Tomato Russet Mite

The tomato russet mite (Aculops lycopersici) is a microscopic pest that causes severe damage if left untreated. These mites begin at the base of the plant, gradually turning leaves bronze or russet-colored as they work their way up. Without intervention, tomato russet mites can kill the plant.

To manage russet mites:

• Use sulfur dust or sulfur-based sprays.
• Remove and destroy heavily infested plants to prevent the spread.

4. Brown Marmorated Stink Bug

The Brown Marmorated Stink Bug (Halyomorpha halys), an invasive pest from Eastern Asia, has become a growing problem in regions like California. These pests feed on a wide variety of fruits, including tomatoes, leaving behind unsightly scars and deformed fruit.

Management Tips:

• Use floating row covers such as Agribon-15 to protect plants.
• Place stink bug traps with pheromone lures away from the garden to monitor and reduce populations.

Other Pests to Monitor

In addition to the pests mentioned, your tomato plants may be at risk from the following:

• Tomato Fruitworm: Damages both fruit and foliage.
• Aphids: Cluster on stems and undersides of leaves, sucking sap and weakening plants.
• Colorado Potato Beetle: Attacks tomato plants as well as potatoes, leaving defoliated plants in its wake.

Organic Pest Management Solutions

Shop Consperse stink bug trap

For a healthy and sustainable garden, opt for organic pest control methods whenever possible. These include:

• Row Covers: Protect young plants from flea beetles, stink bugs, and other pests.
• Companion Planting: Incorporate plants like marigolds, which deter harmful insects.
• Handpicking: Remove large pests like hornworms and stink bugs manually.
• Insecticidal Soaps and Oils: Effective against soft-bodied pests like aphids and mites.

Resources for Tomato Pest Control

If you’re unsure about a pest or need additional information, visit the UC Davis IPM website. This resource offers detailed guides on identifying and managing pests and diseases in your garden.

Protecting Your Tomato Plants

Tomatoes are a gardener’s pride, and protecting them from pests is essential for a bountiful harvest. By staying vigilant, encouraging beneficial insects, and using organic pest management techniques, you can keep your tomato plants healthy and productive throughout the growing season.

Whether you’re battling the notorious hornworm, pesky flea beetles, or emerging threats like the Brown Marmorated Stink Bug, proactive care and thoughtful pest management will ensure your tomatoes remain the star of your summer garden.

Photo Credits

• Beet Armyworm (2004) Nicotine Keeps Leaf-Loving Herbivores at Bay. PLoS Biol 2(8): e250. doi:10.1371/journal.pbio.0020250
• Flea Beetles (2007) Russ Ottens, University of Georgia, Bugwood.org
• Brown Marmorated Stink Bug (2002) David R. Lance, USDA APHIS PPQ, Bugwood.org