Oh no! Someone has been eating my garden!
Suspect #1: Earwigs
Earwigs are typically 1/4 inch to 1 inch long and range from black in colour to brown. They are mostly active at night. Contrary to what their name suggests, earwigs are not a threat to humans and do not crawl in our ears. But, while they may not bite or sting, earwigs have pincers they can use when they feel threatened to give a light pinch. Earwigs mostly feed on dead or alive plants and plant materials as well as dead animals. They most commonly get transported by potted plants, nursery stock, other plant material, or firewood.
Favourite Plants: herbs, corn tassels, dahlias, marigolds, roses, zinnias, berries, apricots, peaches
How to Spot
Because they are mainly active at night, if you notice holes or tears in leaves or flowers in the morning that were not there the day before, it’s likely that you have been visited by some earwigs.
Sometimes earwigs’ black pellet droppings can be seen scattered around your garden.
Prevention & Treatment
One way to prevent earwigs is to surround your garden or potted plant area with rolled-up newspaper or pieces of rigid cardboard as traps. Then, in the morning you can empty these traps into a bucket of soapy water.
Likewise, you can spray soapy water directly onto your plants to help kill any existing earwigs and to prevent any more from invading your garden.
Food-grade diatomaceous earth can be sprinkled in your garden to help keep earwigs away.
References for the above section: 1, 2, and 3
Suspect #2: Aphids
Aphids can be many different colours, including green, yellow, red, white, and black. Aphids do not travel alone but instead they invade gardens in clusters. They start off small, but as they grow they produce offspring that grow wings so they can start expanding their colonies.
Aphids prefer sucking nutrients from stems and leaves of seedlings rather than more mature foliage. They often secrete “honeydew” which is extra sap that they have sucked from plants and has been passed through their bodies. Ants are very drawn to aphids due to their “honeydew” and will guard them to feed the sap to their offspring, often fighting away predators.
Favourite Plants: any plant or tree they can suck nutrients from
How to Spot
If they are big enough, aphids can be found on the upper parts of stems on plants as well as the underneath side of leaves.
Because they suck the nutrients from plant stems, plant leaves can turn yellow or become curled, and it could also cause deformities in flowers, and damage to any fruit a plant may be growing.
Because they secrete excess sap, you can see and feel their sticky “honeydew” on leaves.
Prevention/Treatment
Ladybugs are a great way to prevent aphids. Encourage ladybugs in your garden by planting a variety of flowers and foliage plants and providing access to water.4 You could also purchase some ladybugs to keep in your garden.
Sometimes it's as simple as a strong blast of water. In cases where there are not many, a strong blast of water on leaves can force the aphids to fall off, and it is hard for them to climb back up to the same spot.
A soap and water mixture can also be useful in getting rid of or preventing aphids.
References for the above section: 3 and 4
Suspect #3: Cabbage White Caterpillars
Cabbage White Caterpillars are green with faint yellow lines across their bodies. They also have short, thin hairs that stick up which help them fight off predators such as ants, by releasing chemicals. Before turning into a butterfly, Cabbage White Butterflies start off as an egg that then experiences five larval stages and finishes with metamorphosis into a butterfly. This process can take roughly 30 days to complete.
Favourite Plants: Cabbage, cauliflower, brussel sprouts, broccoli, radishes, kohlrabi, and most perennial flowers
How to Spot
Aside from seeing these caterpillars or butterflies in your garden, you can detect that they have been eating your cabbage or perennials by the holes they leave behind in the leaves or petals.
Prevention/Treatment
As odd as it may seem, planting perennial flowers as a way to deter the Cabbage White Caterpillars and Butterflies from eating away at your cabbage, can be one solution.
Using a fleece or fine netting that can easily be removed by humans can help prevent this pest from getting to your plants. Making sure it is easily removable for humans will make weeding and maintenance much easier.
Food-grade diatomaceous earth can also be used to prevent these pests, as the eggs and caterpillars cannot survive in it.
References for the above section: 6, 7, 8, 9, 10, and 11
References
Coulter, L. How to get rid of earwigs. HGTV. 2022. https://www.hgtv.com/outdoors/gardens/planting-and-maintenance/bug-off-get-the-earwigs-out-of-my-garden
Earwigs. Raid. https://www.raid.com/en-us/bugs/earwigs
Most Common Garden Pests and Solutions. Art’s Nursery. https://www.artsnursery.com/page/garden-pests-solutions
The Editors. How to identify and get rid of aphids. Almanac. 2022. https://www.almanac.com/pest/aphids
Cabbage worm. Grow Veg. https://www.growveg.com/pests/us-and-canada/cabbage-worm-cabbageworm-cabbage-looper/
Jasinski, M. What gardeners should know about the Cabbage White Butterfly. Birds & Blooms. https://www.birdsandblooms.com/gardening/garden-bugs/cabbage-white-butterfly/
Investigating life with the Cabbage White Butterfly and brassicas in the classroom. Fast Plants. https://www.fastplants.org/pdf/activities/Butterfly_Activity.pdf
Cabbage White Butterfly. Australian Museum. 2020. https://australian.museum/learn/animals/insects/cabbage-white-butterfly/#:~:text=Feeding%20and%20diet,%2C%20broccoli%2C%20radishes%20and%20turnips.
BCC Gardeners' World Magazine. Cabbage White Caterpillars. Gardeners World. 2019. https://www.gardenersworld.com/how-to/solve-problems/cabbage-white-caterpillars/
Foggett, C. Outwit Cabbage Whites to save your brassicas. The English Garden. 2019 https://www.theenglishgarden.co.uk/expert-advice/outwit-cabbage-whites/
How to get rid of Cabbage Worms with natural home remedies. Organic Lesson. https://www.organiclesson.com/get-rid-of-cabbage-worms/#:~:text=Apply%20Diatomaceous%20Earth,worms%20by%20piercing%20their%20bodies.