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Leaf Miner - Harmful Farm Insects To Watch Out For

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25 Harmful Farm Insects To Watch Out For

While planting and nurturing an organic farm, the very last thing you want to see are insects, crawling, and wiggling their way to harm your precious green babies.

Sure, some bugs are beneficial as pollinators and predators, and they’re everywhere — your garden box too.

However, while some varieties are okay to have around, such as praying mantises, there are others that are not only a nuisance but can also be downright deadly to your harvest.

Fortunately, there are many natural solutions that can help you rid your garden of bad insects. But first, you need to identify them.

Here is a list of twenty-five harmful insects in agriculture you’ll want to keep an eye out for this season.

1. Caterpillars

Harmful Garden Insects - CaterpillarsIt can be hard to get rid of caterpillars because they are sometimes hard to detect due to their camouflage, protective coloring.

They have a soft body with segmented larvae and around six legs in the front segments and false ones on the rear. They chew on leaves and stems, especially peppers, tomato, eggplants, potato, and tobacco.

Farmers generally refer to those found on tomato plants as hornworms because they have a “horn-like” tail.

2. Cabbage Maggots

Harmful Garden Insects - Cabbage MaggotsImage via www.canr.msu.edu

These crop pests kill plants directly or create an entryway for diseases.

They are commonly found in the cabbage family, particularly the Chinese cabbage, and can be quite difficult to get rid of if not addressed in the early stage.

They cause the most damage in the late summer months, and when they start to attack, the plants will show signs of wilting and shriveling.

Other crops that cabbage maggots feed on include radishes, carrots, brussels sprouts, beets, cauliflower, broccoli, and rutabagas.

3. Cutworm

Harmful Garden Insects - CutwormsPicture via commons.wikimedia.org

Cutworms are most active at night and are found mostly on seedlings and new transplants.

These fat, black, or gray segmented worms mostly chew through stems at ground level and make their way up until the plant is completely devoured.

A cutworm is about 1-inch-long and generally appears during the months of May and June.

4. Aphids (Greenfly)

Harmful Garden Insects - AphidsEveryone knows this dreaded name and it sends a chill down every horticulturist’s spine.

Though often referred to as greenfly or green bugs that fly, these pear-shaped little guys appear in different colors. Black aphids, red aphids, white, brown, yellow, green, gray, or even pink!

They most certainly aren’t picky and like to hang out in large packs. Worse still, they can be found pretty much everywhere in North America, so no farm is truly safe from their wrath.

The thing they crave the most is sap. The little vampires will suck plants dry in days, causing the leaves to wilt and spreading viral illness.

Aphids also carry viruses and can stunt your plants’ growth.

They can be dealt with, however, so the very second you see them, start looking into the most effective ways to get rid of aphids (greenfly) without harming other crops and good bugs.

5. Scales

Harmful Garden Insects - ScalesPhoto via www.flickr.com

The male scale insect looks slightly different from the female.

Females appear as soft or hard bumps on leaves, stems, or fruits, while the males appear as tiny soft crawling larvae with a threadlike mouthpart, or minute flying insects.

Scales suck on sap until the plant is completely weakened. You may notice them having yellow shades, then the leaves begin to drop.

The plant will eventually die if scales are not controlled swiftly. Scales can be found on both indoor and outdoor plants.

6. Earwig

Harmful Garden Insects - EarwigsAre earwigs harmful to plants? Earwigs, on a whole, are beneficial pests. However, when there are too many of them, especially around young susceptible vegetation, they can become aggressive and destructive.

While the damage is generally minimal, they typically go for tomato and pumpkin. 

7. Slugs and Snails

Slugs and SnailsMembers of the mollusk phylum, slugs and snails are most active in gardens where it is damp and/or shady.

You can spot them in well-mulched areas or under rocks. They are most active during the nights and chew large holes into plants while feeding.

They typically attack ripening fruits such as tomatoes, strawberries, and artichokes, as well as leafy vegetables. 

8. Stink Bugs

Harmful Garden Insects - Stink BugsKnown for releasing strange odors, the stink bug is native to North America but can be found across the globe. They are present throughout the seasons and will feed on any vegetable or fruit.

Damage caused by stink bugs generally lead to early decay and spoilage.

Damages on leafy crops and cabbage can be seen in beige or gray blotches. Tomatoes and fruit skins will show darkened or brown bruises in the areas where the pest fed.

Adult stink bugs are not always green. They might also be brown, black, or grayish in color.

9. Grasshopper

 Grasshoppers - How To Get Rid Of Insect Pests In Your Organic GardenHaving the ability to consume approximately one-half of their body weight in one day, grasshoppers can defoliate an entire field in the blink of an eye if you are not careful.

They are voracious feeders that chew on the leaves and stems of a live plant. They are green or brown to reddish yellow in color and are about 1 ½ inches long.

Grasshoppers are so dangerous that some even eat toxic plants. 

10. Thrips

ThripsPicture via www.pthorticulture.com

Thrips are all-rounders as they will suck the juice from leaves, flowers, and fruits. If you notice that your leaves are turning silvery, pale, or splotchy, these critters are nearby.

They feed in large groups and are commonly found in greenhouses and indoor and outdoor gardens.

Their favorite targets are carrots, onions, beans, squash, and flowering plants. Getting rid of thrips is vital for healthy crops and plants.

11. Whitefly

Harmful Garden Insects - WhiteflyImage via www.flickr.com

Commonly found in mass groups on the undersides of leaves, whiteflies suck the sap from plants year-round in outdoor gardens.

The damage caused can be tremendous as they stunt new growths and turn mature leaves yellow. Crops will eventually become weak and vulnerable to other diseases.

Whiteflies also secrete honeydew which turns into black sooty mold. Infestation is usually found on squash, citrus trees, potato, grape, tomato, and cucumber.

12. Mexican Bean Beetle

Garden pests - Mexican Bean BeetlePhoto via commons.wikimedia.org

These little guys look a lot like friendly ladybugs but don’t be fooled. They’re clever copycats.

Mexican bean beetles have a wide diet consisting of lima beans, snap beans, soybeans, and cowpeas.

They’re usually found east of the Mississippi River, though it’s not uncommon for them to be found further south as well, such as Texas and Nebraska and other parts of the world.

These annoying little stinkers like to chew on the underside of leaves, creating a pretty, but aggravating lacy appearance. 

13. Squash Bug

Harmful Garden Insects - Squash BugsSquash bugs! Just what you were planning to do, right? Well, maybe. These particular bugs are any gourd’s worst nightmare, outside of their amusingly appropriate name.

They love the wide, shady, sheltering undersides of road leaves found on pumpkins, squash, and other gourds.

Their eggs look like little smooth, brown pebbles and can be found laid in clusters on the undersides of the leaves of your innocent little gourd. Check out the natural ways to get rid of squash bugs.

14. Blister Beetle

 Blister BeetleThis one is a particularly vivid nightmare for any farmer trying to keep his hay in good shape. This insect has a taste for the stuff and will stop at nothing to munch on it endlessly.

Worse, blister beetles operate in swarms and carry a vicious toxin on them that can incapacitate and gravely injure whatever may swallow them.

Hay that’s been contaminated with the toxin, which is released automatically if the beetles are injured or killed, can be fed to horses and make them extremely sick.

Their coloring is usually bright and a variety of patterns, with shades of gray or brown and yellow stripes running down the backs. 

15. Beet Armyworms

Harmful Garden Insects - Beet Armyworm
Image via entomology.k-state.edu

They’re the larvae of the owlet moth and like to travel in gigantic groups eating everything in sight. They’re capable of traveling immensely long distances in search of munchies.

Their favorite snacks include scallion, cucumber, cabbage, corn, grains, and pretty much anything they get their little mandibles on.

The only time beet armyworms settle down and take a break, is when it’s time to bundle up in a cocoon. The reason they’re dubbed armyworms is that they tend to move in a group.

16. Boxelder Bugs

Harmful Garden Insects - Boxelder BugsImage via commons.wikimedia.org

These instantly recognizable bad garden bugs are a major annual problem in the Midwest.

The red marks on their otherwise black bodies and wings are red veins that stick out prominently in an angular pattern.

Are boxelder bugs harmful? Yes, but they aren’t as big a threat as some of the other bugs on this list since they’ll generally leave your garden produce alone.

You only have to worry if you’ve got fruit trees on your property. The problem with them comes in with their ability to hibernate in groups during the winter.

This means that they’re a double whammy; they’ll invade your orchards in the summer and then they’ll squat in your house in the winter.

And unless you tackle them early on, you’ll be facing their tedious annoyance every year in a vicious cycle.

17. Flea Beetle

 Flea BeetlesPicture via commons.wikimedia.org

What do you get when you cross a beetle with a flea? Nopes. Sheer nopes. These are some extremely tiny, but resilient and persistent little foes. And they’re found everywhere.

Varieties of this family are literally spread globally. They look and act like fleas when disturbed, jumping high into the air and vanishing just as quickly.

Flea beetles can also spread disease among your plants, such as potato blight. Once spotted, it’s strongly recommended to eradicate them as swiftly as possible.

They’ll go for any large-leafed vegetables like potatoes, cabbage, beans, lettuce, and corn. 

18. Black Vine Weevil

Harmful Garden Insects - Black Vine WeevilImage via www.flickr.com

Their targets are ornamental, their preferred favorites being cranberry, strawberry, rhododendron, blueberry, blackberry, and hemlock while in the larval stage.

And you’ll certainly freak out if they ever get in your greenhouse since tender leafed plants are their favorite delicacy. The black vine weevil isn’t one of the most destructive garden bugs for nothing. 

19. Colorado Beetle (Potato Bug)

Harmful Farm Insects - Colorado Potato BeetleAre potato bugs dangerous? Also called potato beetle, Colorado beetles are a potato’s worst nightmare.

They spread out across the entire country and cause devastating damage to potato plants as adults.

They’re easy enough to recognize with their reddish-orange bodies, but by that point, it’s probably too late to nip it in the bud.

And unfortunately, they can be found far outside of just Colorado, so don’t get your hopes up from the name alone. 

20. Striped Cucumber Beetle

 Striped Cucumber BeetleImage via www.flickr.com

Yellow bugs with double black stripes on each wing cover, instantly recognizable. However, there are two common types of cucumber beetles — striped and spotted.

The striped is more common than the spotted cucumber beetle which has spots instead of stripes. Both can cause serious damages.

They feed on cucurbits and the roots of various plants at all stages of life, and as such, can be a force to be reckoned with in your garden.

They’re also deadly to corn where they consume the pollen and protective silk. 

21. Japanese Beetle

Harmful Farm Insects - Japanese Beetle Japanese beetles immigrated in the 20th century and have been wreaking havoc ever since.

Nursery plants don’t stand a chance against this veritable eating machine. Trees? Shrubbery? Salad course and nothing more.

They are a wall of munch, plowing through everything in sight, and travel in swarms, which at least makes them easy enough to spot. 

22. Lace Bugs

Bad bugs - Lace Bugs Photo via www.flickr.com

Now, this is a disturbing little number. They’ve got a lacy-looking membrane covering their wings and upper body and they stick silently to plants and suck up all the nutritious sap.

This leaves your poor plants with absolutely no lifeblood to keep them going.

Lace bugs are easy enough to spot since they essentially plaster themselves to the leaves, looking like a little piece of white fuzz that just got stuck during a breeze. 

23. Leaf Miner

Harmful Garden Insects - Leaf MinerImage via commons.wikimedia.org

A wide variety of different harmful garden pests may be recognized from the burrow-like patterns they leave in the leaves they eat. Winding, twisting white lines are a dead giveaway for leaf miners.

Thankfully, these guys aren’t as much a threat as they are a pest since the damage they do is ultimately minor.

The best way to deal with leaf miners is to remove the damaged leaves and burn them, eliminating traces of whatever may have still been inside. 

24. Mealybug

Harmful Farm Insects - Mealy Bugs Image via commons.wikimedia.org

Mealybugs can be a major hassle since they can even come indoors and attack plants being kept on the windowsill for decoration.

Again, they’re tiny sap-suckers that are found worldwide, and anywhere they manage to infiltrate has got a monster problem on their hands. They look a bit like sticky cornmeal when viewed up close.

Mealy bugs are best gotten rid of by other pest controllers, such as ladybirds since they’re usually far too great in number to handle just by your lonesome. 

25. Spider Mites

 Spider MitesPicture via extension.umn.edu

Spider mites suck out both water and chlorophyll, rendering the plant weakened and floppy even faster than some of the other mentions on this list.

You can tell where they’ve been by speckled patterns flocking the leaves they’ve attacked, and your plants will start to look increasingly lifeless.


Bugs are the ultimate double-edged sword for a farmer, since many are supremely beneficial, like butterflies, ladybugs, and mantises.

These are the garden bugs you want to keep around for the sheer assistance they can give you — everything from pollinating to preying on the things you don’t want in there.

The key to keeping an organic garden alive is to watch out for the bad guys. Everything is looking for an easy meal and your farm is the very center of a massive bulls-eye.

It’s only through due diligence and careful planning and arrangement that you can avoid a potential horticultural tragedy.

This is only possible by paying close attention to what sorts of bad bugs are lurking around and researching the very particular ways in which to deal with them.

Happy farming, my earth-bound friends!

Sasha Brown

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