Onions are very popular crops among gardeners. They are easy to grow, sturdy, require little maintenance, and find multiple uses in the kitchen. Unfortunately, they’re popular among animals as well.
It can be quite annoying to toil all season long for the best onion harvest; only to find out that some animals have taken a good chunk of the bounty. If you know what animals to look out for, then you can protect your beloved onion garden.
What Animals Eat Onions?
Most animals are likely to abandon onions even during the most desperate times. Owing to its high pungency it can cause severe poisoning and other ill effects in some mammals.
However, onions or their plant parts are consumed by creatures such as onion flies, leafminers, cutworms, bulb mites, slugs, snails, rabbits, nematodes, wheat curl mites, grasshoppers, onion thrips, rats, deers, raccoons, and chickens.
Onion Thrips (Thrips tabaci)
Onion thrips are very tiny insects that feed on onions. They’re only about 1-2 millimeters long and can barely be seen by the human eye. However, these tiny insects can cause widespread direct and indirect damage to your onion plants by feeding and laying eggs on them.
Apart from feeding on the plants, these insects are carriers of pathogens that could destroy your whole harvest. Examples of these pathogens are Iris yellow spot virus which causes yellow spots and mottling on leaves, and Pantoea ananatis, the bacteria that causes the center of onions to rot.
How to Control Onion Thrips?
Unfortunately, these insects spread rapidly from one location to another, targeting new plants in the process. Once your garden becomes infested with onion thrips, they can be hard to get rid of.
The best way to manage them is to introduce their natural predators to your garden. These include lady beetles, lacewings, minute pirate bugs, big-eyed bugs, and predatory mites.
Slugs and Snails
Usually, slugs and snails snack on decomposing organic material in the soil. However, if that option is depleted, they have no issues turning to vegetables such as onions for nourishment.
If you discover that your onions are missing the top half or some parts have been bitten clean off, then slugs and snails may be the culprits behind it. One way to know for sure is that they leave a trail of shiny, silver slime behind.
How to Control Slugs and Snails?
Although slugs and snails are sluggish animals, you will be alarmed by the kind of damage they could cause to your onion plants in a short time.
The best way to reduce their population in your onion garden is through cultural practices. Read our comprehensive guide to get rid of slugs and snails in potted plants.
● Roughen the surface around your onion plants with gravel chips or crushed eggshells. Because these critters are soft-bellied, they will have difficulties crawling through your garden to feed.
● Water your onions early in the day and avoid overwatering, as these pests need high humidity levels to thrive.
● Handpick any present slugs and snails in your garden (remember to wear gloves).
● Bury small containers containing beer at the soil level to control slugs and snails.
Cutworms (Feltia subterranea)
Cutworms are nocturnal caterpillars that feed on foliage. At night, they come out of their burrows, encircle the baby plants at soil level, snap them in half, and drag them underground to feed on.
Although cutworms prefer to feed on onion seedlings, sometimes, they cut whole plants as well. Cutworm damage is very easy to identify – the affected plants always appear to have been cut in half.
Although these caterpillars are only about 1-2 inches long, their devastation can be widespread. They can consume an entire garden of onions in one night if their population is high. They’re also active in all seasons, making them very dangerous to your onion plants.
How to Control Cutworms?
The best way to control the activities of cutworms is to prevent them from getting to the plants in the first instance. One way to do this is by creating barriers around the stems of both young seedlings and adult plants.
You can carefully slip an empty toilet paper roll over the young seedling and press it down to bury it a few inches into the soil. For larger plants, you can repeat this with soda cans that have been cut at both ends or rolled cardboards from empty boxes and cartons.
Another way to get rid of cutworms is by physically removing them. Since they are nocturnal animals, go to your onion garden at night with a bucket of soapy water. Pick them off your plants and drop them in soapy water.
Onion Flies (Delia antiqua)
Adult flies of the Delia species do not directly feed on or damage onion plants. However, they lay eggs in the ground that later hatch into larvae. As they grow, these grubs feed on the root, bulb, and stem of the plants.
Onion maggots only grow as long as 10 millimeters. However, if they’re not effectively managed, these tiny larvae will eat more than half of your onion yield within a very short time.
Early warning signs for the presence of onion maggots include the yellowing of the leaves of growing plants. Also, the affected seedlings begin to wilt in patches that spread along the row. However, by the time you begin to notice these signs, it is often too late to save the infested plant.
How to Control Onion Flies?
● Delay onion planting until later in the spring when all the adult Delia flies have hatched.
● Avoid planting successive onion crops on the same patch of soil.
● Avoid planting onions in areas with large undecomposed organic matter.
● Incorporate predatory ground beetles on your field to consume the flies’ eggs, larvae, and pupae.
Onion crops are usually ready for harvest during summer, around the time grasshoppers begin to appear. Grasshoppers will feed on the leaves of onion plants, either entirely or by cutting ragged holes in them.
The worst part is that, because they are capable of camouflage, you won’t notice their presence until they have caused marginal damage to your crop. They also migrate in swarms, so controlling them might be tricky.
How to Control Grasshoppers?
● Use row covers to cover your crops (but be sure there are no grasshoppers on them before covering).
● Introduce natural predators like toads, swallows, praying mantis, and small snakes.
● Till the ground to destroy their eggs.
● Remove weeds regularly.
Leafminers (Liriomyza spp.)
Leafminers are small black and yellow flies that linearly puncture onion leaves to feed on the sap. The adult female flies also lay eggs within the leaf tissue.
Within 2-4 days, the larvae hatch and fold part of the onion leaf to cover themselves from predators and burrow inside the leaf. They also feed on the leaf from inside, creating tunnels that can be seen from outside. This continues until the larvae mature and hatch into adult flies in autumn.
How to Control Leafminers?
Like onion flies, leafminers are difficult to control once they infest your crops. The best way to remove them is by introducing predatory insects like parasitic wasps.
Additionally, you can delay planting until all the adult leafminers have emerged from the soil before planting onions on a previously infested field.
As unbelievable as this sounds, chickens can also eat onions. When added in moderate quantities to their feed, onion has been found to increase their immunity, aid digestion, boost growth, and promote general poultry health.
However, onions can affect the taste and quality of the eggs they lay. If you have a chicken farm, it might be a good idea to protect them from your onions and vice versa.
How to Control Chickens?
Fortunately, it is very easy to manage chickens and keep them away from your onions. All you need is a mesh around your onion garden, and you’re good.
Onions are pretty toxic to rabbits. Fortunately, rabbits are good at self-regulating vegetables that are good for their health and, in the wild, will leave your onions alone. However, if they cannot find anything else to feed on, they WILL eat onions.
How to Control Rabbits?
● Use a mesh to create a barrier around your garden.
● Plant onions with other crops that they find repulsive including, garlic, basil, mint, and rhubarb.
● Find and remove their nests from your garden. However, check all legal implications before doing so.
● Use visual deterrents to scare them away. Examples include rubber snakes and owl statues.
Bulb Mites (Rhizoglyphus spp. and Tyrophagus spp.)
Bulb mites are tiny insects that infest many bulbs, including onions. Depending on the species, they are either yellowish-white or pink and never grow longer than 0.5-1 millimeter.
The female insects have a short lifespan but can wreak havoc in that short time. They infest the onion bulbs both on the field or in storage.
How to Control Bulb Mites?
Bulb mites are difficult to control once they infest an onion field. However, the introduction of predatory mites can help to lower their numbers.
Wheat Curl Mites (Eriophyes tulipae)
Wheat curl mites are tiny insects that usually feed on onions after they have been harvested and placed in storage. They are only about 0.01 inches long.
When they infest onion crops in the garden, they first feed on the foliage before working their way down to the sprouting bulbs. Their presence can cause the bulbs to rot or dry out.
How to Control Wheat Curl Mites?
● Rotate onions with other broad-leaf crops like canola, sunflower, and field peas.
● Plant onions early in the season when temperatures are below 50℉.
● Till the field for 2 weeks before planting the onions.
Nematodes are herbivorous microscopic roundworms. They infest the soil, burrow inside the plants, and feed on the roots, bulbs, and stems.
The most common nematodes that feed on onions include the bulb nematodes (Ditylenchus dipsaci), lesion nematodes (Pratylenchus penetrans), stubby root nematode (Paratrichodorus spp.), and root-knot nematodes (Meloidogyne spp.)
Once a nematode infests an onion, they leave an opening for other pathogens and microorganisms in the soil. This causes the onion to rot from the inside out.
How to Control Nematodes?
● Plant onions in the early spring as nematodes are less active then.
● Practice crop rotation with vegetables from unrelated families.
● Weed out nematode-infected plants and till the ground before planting.
● Plant nematode-suppressing crops like marigold, castor beans, partridge peas alongside your onions.
Now that you know what animals eat onions, you know what to look for when protecting your precious plants. Always plan ahead and use precautionary measures wherever possible.