What’s Eating Holes in Your Lettuce? Identification Guide

Lettuce or Lactuca sativa, is a leafy green harvested as a food source. The plant is tasty, high in minerals, and used in a variety of dishes, including salads, soups, and juices. However, it’s common to see holes in lettuce grown in gardens and farms, usually caused by insect and animal pests.

Here’s a list of what could be eating holes in your lettuce:

  1. Aphids
  2. Caterpillars
  3. Greenhouse whiteflies
  4. Leafhoppers
  5. Slugs and snails
  6. Fungus gnats
  7. Beetles
  8. Spider mites
  9. Thrips
  10. Crickets
  11. Herbivores

The kind of damage left behind on your lettuce can be a significant indicator of the type of pest that has been snacking on the plant, and this information can help decide on the best way to protect your lettuce. In this article, I’ll take you through the main pests that can attack your lettuce and how to identify them.

1. Aphids

The lettuce plant is affected by a wide range of pests that mostly eat its leaves and cause holes of different shapes and sizes to appear. These pests are primarily insects, but herbivores like rabbits, deer, and mice may also feed on lettuce.

Aphids are little, winged or wingless, oval-shaped insects with tiny heads, a pair of black cornicles, and a cauda projecting from the abdomen. They come in a range of colors, including gold, red, black, and green.

These pests feed in colonies and cause holes in leaves and mottling of plants. Aphids also regularly transmit viral infections and release honeydew, on which sooty mold grows.

Aphids are the most common pest in agriculture, and it’s typical to find them on the undersurface of leaves. Plants in the area, as well as individuals and animals that have recently come into contact with them, can transfer aphids to your lettuce plants.

Aphids also thrive year-round and can be found in indoor and outdoor environments.

These critters feed on the fluids they suck from plants, using their mouthparts to pierce the exterior of leaves and stems, which may cause distorted and deformed growth in the plants. Aphids typically feed in large groups on new plant growth or the bottom parts of leaves. They also require a lot of plant fluid for sustenance and usually feed on the plant until it dies.

Aphids feed in droves, and a mass of tiny insects around the top leaves of your lettuce plant accompanied by wilting leaves and stems is a sign your plant may be affected by these pests. T

hey can also be identified by yellowing and deformed leaves in lettuce, affected stem development, and an ugly black sticky material on the plant.

Ants and aphids have a well-known symbiotic relationship, with ants guarding aphids and even assisting them in moving from one location to another in return for eating the secretions left behind by the aphids. So if you see ants traveling between your plants in the garden, there’s a good chance you have aphids present too.

2. Caterpillars

The most bothersome pests for most lettuce farmers are caterpillars that munch on leaves. Caterpillars are the larval phase of various butterfly and moth species, and they can be very destructive.

Moths and butterflies prefer to deposit their eggs near food sources, like lettuce plants, so their offspring don’t have to wander far when they hatch.

Caterpillars come in various colors and sizes, but they’re primarily brown or green worms with black excrement and leave holes that run through lettuce leaves. They’re also tough to spot since they hide on the undersides of leaves and against leaf stems to blend in. Caterpillars are typically easier to spot once they’ve finished resting, as they’ll begin to move around.

It becomes apparent somewhat quickly when caterpillars are present in lettuce farms, as the plant’s leaves will typically be severely perforated in many places.

You can also often observe excrement left behind by the caterpillar, sometimes before you notice the insects themselves. Caterpillar excrement can range in color from brown to green, and it’s usually slimy and moist, making it easier to see the feces in a sea of green vegetation.

Caterpillars thrive during the summer and fall seasons and are mostly found in lettuce plants grown outdoors.

The three most important caterpillars that affect lettuce are the beet armyworm, the cabbage looper, and the cutworm. All three species of caterpillars damage lettuce leaves similarly, chewing through the plant’s leaves.

3. Greenhouse Whiteflies

Whiteflies, who look just like their name, are moth-like insects typically 0.06 inches (0.15 cm) long, found with small yellow larvae and green, oblong, flat, motionless nymphs and pupae. They’re tiny, flying insects related to aphids and scale bugs.

Whiteflies are a kind of sap-sucking bug that can wreak havoc in the garden and severely harm lettuce. They can be seen in clusters on the underside of leaves, extracting and eating the juice from the lettuce.

Whiteflies also secrete a thick fluid called honeydew, which can induce fungal infections and render plants incapable of photosynthesis.

The insect thrives in late spring and summer and may affect lettuces grown indoors or outdoors. Whitefly adults and nymphs feed on plant juices, resulting in feeble plants, yellow leaves, withering, and even loss of leaves. Infested lettuce plants are frequently covered in honeydew, sticky whitefly feces.

A sticky coating on the foliage, yellow leaves, and slow development of the lettuce plant are the most common indicators that your lettuce is infested with whiteflies.

Inspecting the insects you discover on the plant might help determine whether you have whiteflies. The insects are usually found on the back of the leaves, so it’s good to look on the underside of lettuce leaves to check for them.

Nevertheless, because whiteflies are so little, you may not spot them until they’re buzzing over your garden or farm. Typically, late spring is when the insects lay their eggs, which hatch about a month later. Whiteflies also prefer warm, humid temperatures and thrive in greenhouses.

4. Leafhoppers

Leafhoppers are wedge-shaped pests with a green body and yellowish to dark green to black markings that can grow up to 0.16 inches (0.41 cm) long. Leafhoppers rarely fly, but rather the insect leaps sideways, forwards, and backward to move. They also suck juices from the underside leaves, making the leaves crumple and curl upward.

Leafhoppers have piercing and sucking mouthparts to attack and feed on most leafy vegetables, including lettuce. They can also induce leaf yellowing, while adult and nymph leafhoppers inject toxins into plants which can cause diseases and leave the plant susceptible to viral attacks.

The aster leafhopper is one of the most prevalent leafhopper species that affect gardens and farms, and it’s responsible for spreading the aster yellows disease to lettuce.

Although most of them move south in late April, the aster leafhopper may survive the winter in meadows and small grain farmlands, meaning that their damages to your crop can be spotted all year round.

Leafhopper infestation in lettuce is characterized by yellowed leaves and stems in infected plants, as well as wilted and twisted leaves. The adult and nymphs of leafhoppers eat away at the tissues that transport manufactured food from the leaves to other plant areas, leaving the attacked leaves yellow and wilted. This conditions is called hopperburn.

Leafhoppers seldom infect farms in large numbers, so yield loss might occur at low levels before symptoms appear. Use sweep nets to scout the lettuce plants for adult leafhoppers and look below the leaves for nymphs frequently.

In addition, look for any signs of hopper burn on the lettuce leaves. If you find leafhoppers, place them in a freezer-safe container with methylated spirit to prevent them from escaping before you can examine them thoroughly.

5. Slugs and Snails

Unlike the preceding pests in this article, slugs and snails aren’t insects but land-dwelling mollusks with soft bodies that feed on the leaves and stems of plants. They might be a range of colors, including gray, black, or speckled, and they often leave a slime trail behind them, causing severe damage to seedlings and sensitive crops.

Slugs lack a shell, but snails have distinctive shells on their bodies.

Snails and slugs like to congregate in moist, dark areas, such as among plant waste and compost, behind rocks, and among low weeds. They also eat both live and dead plant matter.

Snails and slugs are most active at night. So the evidence they leave behind, such as a slime trail as they go, destruction to seedlings, and plants with big, oddly shaped holes, would most likely be visible instead of the pests themselves.

Slugs and snails are rarely seen during the day since they eat at night or on wet days. However, evidence of infestation on lettuce is easy to notice. Rough holes in the lettuce leaves, bitten parts on the leaf edges, and trails of glossy slime are all signs that your lettuce is infested.

Slugs and snails are most likely living on your farm if you have plant pots, heaps of yard trash, or other forms of waste scattered around your garden.

6. Fungus Gnats

Fungus gnats are minuscule flying insect species that feed on organisms that form on the surface of seedlings’ growing medium. They deposit their eggs in the soil, which hatch into tiny, white worms. Adult fungus gnats can be a severe irritant to lettuce, and their larvae will damage seedlings’ health or growth.

Fungus gnats thrive in wet soil and come in a variety of shapes and sizes. They settle down and lay their eggs on solid ground, where they’ll hatch. The larvae that follow will target seedling roots, eating as much as possible before pupating.

The gnats can be seen buzzing above the plants or wandering fast across the surface of leaves or soil after emergence. Unfortunately, the soil is almost certainly contaminated by the point fungus gnats are discovered.

Fungus gnats thrive in farms and gardens year-round and are well-suited for indoor and outdoor environments.

7. Beetles

Beetles are destructive insects that attack practically every part of a plant, including the stems, roots, and leaves, and can transmit illnesses like fungal wilt and mosaic virus. They’re noted for causing serrated leaves, uneven patches, and leaf window panning.

Bagrada beetles, cucumber beetles, seedcorn beetles, click beetles, darkling beetles, and flea beetles are the most frequent species of beetle that attack lettuce.

Harlequin Beetles

In adults, Harlequin Beetles have a bowl-shaped body roughly half an inch long (1.27 cm). They’re brilliantly colored, usually black and yellow or black and red, although their color patterns might change according to the season. Harlequin beetle eggs are small white barrels ringed by black bands and topped with a black crescent.

Harlequin beetles hibernate on old plants over the winter and produce eggs in the spring. They appear in rows on leaf undersides in small clusters. White dots on the foliage and leaves that seem dark and torn are signs of harlequin beetle activity.

Darkling Beetles

Darkling beetles are tiny black or brown insects approximately a quarter of an inch (0.64 cm) in length. They’re mainly nocturnal and usually infiltrate the garden through weeds or grasslands nearby. Their antennae differ from those of other beetles as the tips of their antennae are frequently larger.

Some beetles are suitable for gardens because they consume garden pests. On the other hand, darkling beetles devour lettuce seedlings and leaves.

Flea Beetles

Flea beetles are soil-borne and can spend the whole winter season in the soil, garden trash, or bush. This long hibernation period implies that the flea beetle is an incredibly tenacious species to manage. Flea beetles can also jump a vast distance, thus their name, which refers to their ability to resemble the leaping power of a flea.

Cucumber Beetles

Cucumber beetles have a yellow or green head and abdomen and are tiny, oval-shaped insects. Seedcorn beetles have dark brown wings with bright colored stripes. Wireworms, sometimes known as click beetles, are dark brown with short hairs and a massive tooth-like protrusion.

Beetles, like aphids, may transfer bacterial and viral plant illnesses through their mouthparts and droppings, so the damage can worsen if the problem isn’t discovered and fixed right away. They like plants that are weak, overgrown, or lack light.

While beetles don’t usually kill mature plants by munching their leaves, a nasty infestation can have a substantial influence on plant health and negatively affect your crop.

Beetles usually thrive in the spring and summer and typically affect outdoor plants. Beetles are prevalent on lettuce during this period.

8. Spider Mites

Spider mites are color-changing arachnids that turn green to orange or scarlet when the temperature drops. They rob the leaves of chlorophyll by sucking on them, resulting in white transparent patches and a silky network of webs that can blanket the entire crop.

Spider mites have a lot in common with spiders and ticks.

Spider mites are so tiny, so you’ll only be able to spot them by the yellow spots and thin webs they create on leaves. Their webbing is quite delicate; thus, the undersides of leaves will seem dusty. Often, leaves affected by spider mites are brown or seemingly bleached.

The leaf discoloration spider mites leave behind looks like mineral deficiency, so be cautious to check for the pests while adding fertilizers and closely monitor the pH of your water. Tapping a leaf on a piece of white paper to see whether it has mites on them is a good idea. Spider mites will often fall from infested leaves and onto the paper, which will be seen under a microscope.

Spider mites are difficult to eradicate. They’re adept at invading drought-stressed plants and may swiftly take possession of unwatered plants or leaves. They prefer hot, dry settings and may grow indoors and outdoors.

9. Thrips

Thrips are small flying insects with slender bodies that are practically diamond-shaped. They feed on the leaves and blossoms of plants, creating tiny spots, sores, and downward curling leaves. The bright green, yellow, or black bugs swarm in enormous numbers, wreaking havoc on leafy greens.

If thrips aren’t managed as soon as they appear, they can reproduce quickly and damage lettuce crops in weeks. These insects like to deposit their eggs in the leaves of the plants they affect, making them hard to eradicate.

The size of thrips makes them challenging to locate, so when they appear, they’ll most likely be in large clusters. Thrips, like aphids, feed on lettuce plants by puncturing leaves and draining the fluids out of them. Thrip damage appears as light or patchy yellow discoloration on the leaves of plants.

Thrips adults and nymphs infest the undersides of young leaves and developing points, puncturing the leaf surface and sucking out the contents of the leaves. Silvery-white patches signify the presence of thrips, and younger leaves afflicted will become deformed, with growing tips dying. Thrip populations usually peak in gardens and farmlands within four weeks of emergence.

The insects usually thrive in the spring and summer months and mostly infect lettuce grown outdoors.

10. Crickets

Adult field crickets are 0.6 to 1 inches (1.5 to 2.54 cm) in length with long antennae and a lustrous black-to-brown coloration. Field crickets come into the garden like darkling beetles—from nearby fields, mainly cotton fields or uncultivated regions. Although they’re not frequent lettuce pests, if they’re there, they can damage your lettuce crop by consuming seedlings.

Crickets are uncommon lettuce pests mainly restricted to farms with irrigation systems. However, crickets are a significant source of concern during nursery growth, as they may quickly cause damage to rows, if not the entire field, by slashing young plants shortly after emergence.

The nymphs of crickets emerge early in the spring, starving and eager to consume whatever they can chew through, such as lettuce leaves and seedlings. Adult crickets eat a variety of lettuce and other types of plants. 

Crickets don’t usually cause significant damage or constitute an infestation, but their overpopulation can create unsightly holes in the greenery around the garden.

11. Herbivores

Herbivores live on a strict diet of plants, and it should come as no surprise that they can also cause holes in your lettuce. The most common herbivores that affect lettuce are field mice, rabbits, and deer.

They leave behind similar kinds of damage on lettuce leaves, and you can tell if your lettuce was affected by herbivores by checking for teeth and bite marks.

Rabbits, in particular, are growing more numerous in urban areas, putting lettuce crops in jeopardy. Rabbit damage is visible because they eat everything, and they eat a lot. You may, however, safeguard your plants by erecting a rabbit fence or enclosing them in a cage.

Is It Safe to Eat Lettuce With Holes?

Lettuce is a leafy edible legume that matures in 1 to 2 years, and its size, shape, and leaf type vary widely. Generally, the plant’s leaves create a dense head, and its stem is short, with bigger leaves at the bottom and smaller leaves as you go up the stem. The plant’s green or crimson leaves are usually smooth or curved, and lettuce may grow 11.81 to 39.37 inches (30 to 100 cm) tall.

Vegetable farmers or gardeners typically harvest large amounts of lettuce, and it’s pretty common to see some plants with holes in them. Still, it’s always best to be cautious.

It’s not always safe to eat lettuce with holes. Lettuce that has one or several holes is a telltale sign your produce has been tasted by insect or animal pests. It may also indicate the plant is sick or have mold and rot. Therefore, always inspect the crop properly before turning it into a meal.

Although these pests can range from very destructive insects to relatively tame bugs like whiteflies, it’s normal to have second thoughts about eating their leftovers.

Some pests, such as slugs, might leave behind unsavory parasites or microbes that could cause severe harm if ingested.

Moreover, It’s best to avoid plants with rot, mold, and yellowed leaves.

Look for clues that an animal has been nibbling on the leaves and inspect the ground nearby. Don’t consume the lettuce if there are mounds of deer or rabbit feces in the area. These animals can transmit severe E. coli and salmonella variants that can cause serious harm to small children and the elderly.

Dr. Moritz Picot

Dr. Moritz Picot is a horticulture enthusiast and the founder of TheGrowingLeaf.com, where he serves as the lead content writer. He established the website in 2022 as a valuable resource for both gardening aficionados and beginners, compiling all the gardening tips he has accumulated over the past 25 years. Alex has a passion for nurturing plants, transforming backyards into inviting spaces, and sharing his knowledge with the world.

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