Zinnias are among the most beautiful flowering annuals that are super-easy to grow. There are several cultivars of this plant that come in different sizes – some taller varieties can grow up to four feet, while dwarf or compact ones reach just a few inches in height. Zinnia varieties are also available in different colors, shapes, and flowering styles to spoil you with a wide range of options.
Zinnias are prolific bloomers and can turn any dull-looking landscape or garden into a riot of color. Aside from their bold and colorful flowers, gardeners also love growing zinnias for their ability to attract birds and pollinators into the garden.
Unfortunately, zinnias are also a favorite among destructive pests, and waking up to see entire leaves destroyed on your zinnias before they have even flowered can be heartbreaking. It might also leave you wondering what it is that is eating your zinnia leaves.
Keep reading below, as we might just have the answers and solutions you are looking for!
What is eating my zinnia leaves? – Common culprits
We all dread seeing our hard-earned flowers being feasted upon by pests! Unfortunately, however, these pests are a part of the ecosystem and are therefore everywhere. But you do not need to repeat the trauma after your first batch of zinnias has been devastated. Instead, do some investigation to identify the real culprit, so you can come up with clever ways to get rid of them for good.
Check out the most common zinnia pests below and see if any of them match the signs and symptoms of your plants:
Aphids are a common enemy in the garden. Whatever you plant in your backyard, these pests are unlikely to overlook any attractive or healthy-looking leaves. Several species of aphids can infest a garden, and black bean aphids are the most common pests that attack zinnias.
If you have sharp eyesight, you might notice these tiny creepy crawlies feeding and hiding in the foliage of your precious zinnias. They are oval-shaped, like a grain of rice, and come in different shades such as dark green or sharp black.
Aphids attack your plants by puncturing their leaf surface to feed on the sap inside. Aside from creating holes in the foliage, they also leave their byproduct – known as honeydew – on the leaves, and this in turn can attract other insects like ants. Sooty mold fungus can also grow on these sugary deposits and can turn the plant’s stems and leaves black.
If you think your zinnias have been infested by aphids, here are some good tips to get rid of them:
- For smaller infestations, blast the leaves with a water hose to dislodge the tiny insects.
- Spray the affected leaves with neem oil, horticultural oil, or a mixture of water and dishwashing soap.
- Apply diatomaceous earth to kill the pests. However, do not apply it if your plants are in their blooming cycle, as this product can kill beneficial insects like bees and butterflies.
Caterpillars have a voracious appetite for almost any kind of herbs, vegetables, and flowers in the garden. Unfortunately, your pretty zinnias are also on their list of favorites. These wiggly garden visitors are nocturnal pests, so it might be challenging to catch them in action. If your zinnias’ leaves have large holes with circular chew-marks, then you are likely dealing with a caterpillar infestation.
Three types of caterpillar can attack zinnia plants, and these are:
- Leafrollers: These worms have yellowish-brown bodies and black heads, and turn into moths when they reach maturity. Leafrollers love to devour the leaves, flowers, and flower buds of your favorite plants.
- Armyworms and cutworms: These worms grow from tiny green worms into black, gray, or brown caterpillars. Without your intervention, they will consume your plants to bulk up as they prepare for their pupal life-stage.
- Cabbage looper larvae: Cabbage loopers are usually light green with white lines along the sides of their bodies. Like the other caterpillars, they, too, love to devour the flowers and leaves of your zinnias as they grow bigger.
So, now that you know you have a caterpillar infestation on your hands, how do you get their population under control? Here are the steps to eliminate them:
- Remove the weeds around your plants to avoid attracting caterpillars.
- Apply Bacillus thuringiensis to the affected plants.
- Invite natural predators like parasitic wasps, lacewing larvae, or tachinid flies to manage the population.
- Spray neem oil or a solution of water and soap to naturally eliminate the worms.
Earwigs are tiny, nocturnal insects with a pair of protruding pincers that they use to catch their prey. These pests are omnivores – their diet includes insects as well as decaying plant matter. Among the favorites of these garden scavengers are aphids, plant lice, insect larvae, and small snails. Hence, as you might have guessed, they are not totally bad – earwigs are also vital to keep other destructive insects under control.
The problem arises when the earwig population grows out of control and their natural food sources become limited. Various herbaceous plants, vegetables, and flowers can be a tasty option for these tiny pests, and yes – that includes your zinnias. One tell-tale sign of an earwig infestation is the appearance of tiny holes at the center and sides of your zinnias’ leaves.
Here are some quick solutions you can follow to keep an earwig infestation under control:
- Mix one part 70 percent rubbing alcohol with one-and-a-half parts water in a spray bottle. Use this solution to spritz the earwigs on the leaf surface.
- You can also use other natural repellents with strong scents, such as lemon, rosemary oil, eucalyptus oil, basil, peppermint oil, and white vinegar.
- Apply petroleum jelly to the stems of your zinnia plants.
- Mix equal parts olive oil and soy sauce to create oil pit traps. Pour the mixture into a container with small holes in the lid, and bury the container in the soil near the base of your zinnia plants. Check your oil trap every morning for earwigs, and replace the mixture as needed.
4. Slugs and snails
Other nocturnal pests that can wreak havoc in your garden are slugs and snails. These crawlers are famous for the slimy trails they leave in the garden, and for the raggedy holes they chew in your plants’ foliage. If these symptoms are apparent in your flowering plants, then slugs and snails may be the garden enemies you are dealing with.
If you are troubled by a slugs or snail infestation, try the solutions below to keep them off your garden plants:
- Use a beer trap. Simply fill a container with beer and place it near your zinnia plants.
- Place sandpaper at the base of your zinnia plants to repel the pests.
- Introduce natural predators such as geese, frogs, nematodes, or birds.
- Surround your zinnias with snail-repellent plants such as nasturtium, rosemary, lantana, sage, lavender, geranium, poppy, fuchsia, or hostas.
- If you prefer a more aggressive solution to eradicate the slugs and snails, you can use iron phosphate, pesticides, bleach, and other snail-control solutions. However, keep in mind that these solutions might harm your plants as well as the other animals in your garden, so use them with caution.
5. Japanese beetles
If your zinnias are left with skeletonized leaves, then Japanese beetles might be your culprit. These pests are usually about an inch in size, so unlike other tiny pests, they are more visible to the naked eye. Their heads and bodies are covered with metallic blue-green and copper, and the sides of their bodies are lined with small tufts of white hair.
Japanese beetles usually attack during the summer season, consuming the delicate petals and leaves of your zinnias. They usually bore holes into the flowers and feed on the plant tissue between the veins of the leaves.
If you have a Japanese beetle infestation on your hands, here are some effective ways to eradicate them:
- Spray neem oil on the infested leaves.
- Spray a mixture of water and dishwashing soap on the leaves to suffocate the pests.
- Use Japanese beetle traps to lure the bugs and keep them away from your plants.
- Add parasitic nematodes to your garden to manage Japanese beetles and other pest populations.
- Plant geraniums around your zinnias to repel the bugs.
Other causes of foliage damage in zinnias
Sometimes, a damaged zinnia leaf might look like it has been chewed on by an insect, but there are certain leaf diseases that can cause similar symptoms, so make sure to investigate thoroughly before taking action.
For example, bacterial and fungal leaf spots can cause tiny, circular holes in your zinnias’ leaves. Eventually, this can lead to unwanted black spots and rotting of the plant tissue.
Occasionally, curious animals like deer and rabbits might also damage the leaves of your plants. Rabbits generally do not eat zinnia leaves, but it is always possible that they might have a nibble on any random leaves they find – even your zinnias.
So, carefully observe the appearance of the damage, and monitor your garden if you can. You can also use devices such as wireless cameras to catch the real culprit at night time. Once you get to the bottom of this, you will be able to employ the best strategies to keep the pests from setting foot in your flower beds again!
Zinnia plants can have several garden enemies, so never let your guard down! Pests like caterpillars, slugs and snails, Japanese beetles, aphids, and earwigs can all destroy the fruits of your labor. Hopefully, you will identify the culprits of your ruined garden, and use the tips in this guide to get rid of the infestation for good!
Image: istockphoto.com / Elisa Irmalia