Plant Pest Identification

Updated April 17, 2017

When you think of plant pests, you probably immediately think of insects that eat or otherwise damage plants, but there are other sources of plant problems, including animals (vertebrate and invertebrate) and diseases. Even other plants, such as aggressive weeds, can be destructive to your garden. Various pest management approaches can assist you in keeping all manner of pests from harming the plants you hope to grow, harvest, and enjoy.

Vertebrate Pests

Vertebrate pests (creatures with backbones) include birds, mammals, and reptiles. Those pests can be as tiny as mice or as large as deer or in some places bears. Some common bird pests are swallows and woodpeckers. Common mammals that damage garden and yard plants include squirrels, gophers, raccoons, skunks, rats, mice, opossums, and rabbits. Lizards and snakes represent the reptile pest population, although many of those eat insects and small mammals and can therefore be beneficial to your garden.

Vertebrate pests are easy to identify as they are visible and leave evidence of their presence. Deer, for example, which might come into your garden to eat your strawberries, can leave a wake of trampled plants in their path, as well as hoof prints and droppings.

Invertebrate Pests

Invertebrate pests (creatures without backbones) include insects, mollusks, mites, and nematodes. Those pests are usually very small and often difficult to see, although the damage they can cause to your garden is evident. Some common insect pests are ants, aphids, beetles, caterpillars, centipedes, cockroaches, moths, and grasshoppers.

Spider mites are the most prevalent garden pest and look like tiny dots moving around on the leaves of your vines, vegetables, and other plants. Snails and slugs leave slimy trails and chew smooth-edged, irregular holes in seedlings.

Nematodes are microscopic worms that live in the soil and feed off the roots of your plants; however, some nematodes are beneficial as they feed on harmful insects rather than your plants.

Not all invertebrates are bad for your garden. Earthworms help keep your garden soil well aerated. Bees and butterflies help pollinate crops, flowers, and fruit trees. Wasps, ladybirds, spiders, and other predators may help keep your insect-pest problems under control. Always keep in mind that broad-spectrum insecticides can kill beneficial invertebrates as well as pests.


Most diseases affecting plants result from fungi, although some are caused by bacteria or viruses. For example, leaf curl is caused by a fungus that appears as thick, puckered, reddish spots on the leaves of peach trees. The tree may lose its leaves and be vulnerable to sunburn, or become twisted and misshapen. Fire blight, which affects pear, quince, apple, and crabapple trees, is caused by bacteria that invades the tree and causes a dark liquid to ooze from cankers (open sores) on the bark.


In addition to the common weeds that infest your garden---dandelions, crabgrass, nettles, bindweed--- invasive plants can also filch the nutrients and space your flowers and vegetables need. Those invasive plants are not native to your area but thrive in the environment, taking over fields, grasslands, and gardens. These plants are usually introduced to a new area by landscapers and include the Russian olive, capeweed, ground ivy, and a variety of brooms. Probably the most famous example is the kudzu, an ornamental vine from Japan that now covers millions of acres of the American Southeast.


Determine your pest management regime by identifying the cause of the damage to your flowers, vegetables, shrubs, and trees. Try methods that do the least harm. For example, instead of spraying weeds with weed killer, try hoeing the weeds out of your garden or planting ground cover that discourages weeds. Introduce natural enemies to the pests that are harming your garden. Dragonflies, lizards, and toads will eat many insect pests. A plastic owl on your rooftop will frighten away hungry birds. Some people claim that spreading dog or human hair in and around a garden will discourage deer. Cats and dogs can eradicate mice, rats, and squirrels. If all else fails and pesticides are your only option, make sure you are addressing the appropriate pest.

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About the Author

A freelance writer for more than 30 years, D.M. Gutierrez has had nonfiction, fiction and poetry published in women's, mystery, academic, children's, disability and teen print publications and websites including "Psychological Reports" and "Highlights for Children." She has an advanced degree in psychology from the University of California at Davis.