How to Deal with Diamondback Moth Pests in Your Garden

Dealing with insects in the garden is something no one wants to deal with, but it happens to all of us from time to time. Diamondback moths are pests that attack all plants in the cabbage family. The larvae do the most damage, feeding through the leaves and potentially destroying your vegetables.

If you’re growing brassicas and you’ve had some pest damage, you may have a diamondback moth problem. Here’s what you need to know.

What is a Diamondback Moth?

Diamondback Moths (Plutella xylostella) are night-flying moths that originated in Europe but migrated to the Americas, Asia, Australia and New Zealand in the mid-1850s. If you live somewhere where you can grow cabbage, these pests are sure to happen.

Often compared to cabbage loopers, these moths lay eggs that hatch into larvae that can actually damage your crops.

Gardeners usually see adult versions, which are small, slender, grayish-brown moths with long antennae. They don’t last very long; Males live for 12 days, and females live an average of 16 days. There is enough time for these insects to lay eggs and start the life cycle again.

Diamondback moths overwinter in temperate regions, but if you live somewhere with cold winters, chances are they won’t survive. The bad news is that they re-invade these areas in the spring.

Diamondback moths primarily attack plants in the Crucifera family, such as:

  • broccoli
  • brussel sprout
  • Cabbage
  • Chinese cabbage
  • cauliflower
  • collard
  • cauliflower
  • kohlrabi
  • Mustard
  • Radish
  • turnip
  • water hyacinth

Lifecycle of Diamondback Moth

The female diamondback moth lays about 250 to 300 eggs, but lays an average of 150 eggs before she dies. Their eggs are oval and flattened, usually only .44 mm long. They are yellow or pale green, and females lay them in small groups on depressions on the leaf surface. Within a week, these eggs turn into larvae.

The larvae are active and small, moving around and moving down the plant on silk strings. In the beginning, the feeding habit of the larvae is leaf mining, but since these pests are so small, you probably won’t notice them. Then, they molt on the underside of the leaf and feed on the underside of the leaf.

Only then do they start chewing the leaf seriously and do real damage.

The next stage is the pupa, which grows in a loose silky cocoon on the lower or outer leaves. It takes about 9 but up to 15 days. This is the stage before it turns into an adult diamondback moth.

As mentioned earlier, adults only live for three weeks, at least. They lay eggs and die shortly after. The diamondback moth’s total lifecycle takes 50 days, so depending on where you live, these moths develop up to four generations or 12 generations each year.

This is problematic!

Symptoms of Diamondback Moth Infection

While dealing with diamondback moth larvae is frustrating, these pests are not as destructive as others, unless the infestation becomes very large. Using proper gardening and prevention techniques will go a long way towards avoiding a serious problem.

So, how do you know if you have a diamondback moth infection? You have to look for plant damage caused by these pests, which occurs during the larval stage when they feed on plants.

The larvae may be small, but they are numerous and destructive. Here are some common symptoms of a diamondback moth infection.

  • presence of silk on plants
  • Skeletal leaves except for leaf veins
  • Damage first starts with lower leaves
  • Damage to the underside of the leaf, leaving the upper epidermic intact, producing a window-pane effect
  • Head formation problem in Cabbage, Broccoli and Cauliflower

How to Stop Diamondback Moths

Preventing pests in your garden is always easier than getting rid of them, so it is best if you take early measures to prevent diamondback moths. Here are some tricks to try.

Use floating row covers

If adult diamondback moths are unable to lay eggs on your plants, you won’t need to worry about infestation. Putting a floating row cover over your plants prevents moths from reaching your plants.

It doesn’t help, however, if they overwintered in your soil and emerge under row cover. It can help to turn the surface of the soil in early spring to expose pests.

Plant Pest Free Transplant

Another pest-management tip is to use seedling transplants that are free of larvae or any potential contamination. Check for certified pest-free plants when you go shopping.

watch for pests

As always, gardeners should keep an eye on their crops and regularly check for possible pest damage. Monitoring for larvae or feeding damage means you can deal with any problems as quickly as possible.

how to get rid of diamondback moth infestation

The problem with diamondback moths is that they are known to have insecticide resistance; It started in the 1980s. At this point, most insecticides available in stores are ineffective, so if you encounter these pests in your garden, you may wonder what you can do to get rid of a diamondback moth infestation.

always rotate crops

Since diamondback moths have a narrow range of hosts and feed only on cruciferous plants, crop rotation is one of the prime ways to take back control of your garden. These pests thrive in soil in many places, so make sure you avoid replanting the same crop in the same garden area. This is an easy way to reduce the number of pests and damage to your crops.

Use bacillus thuringiensis

if you apply Bacillus thuringiensis (Bt) When you notice these pests on your plants, it can be an effective way to control diamondback mites. You want to make sure you cover the plant properly and use it as directed. It often needs to be applied more than once to effectively control this pest population.

Keep in mind that this insect has also developed resistance to Bt, so alternate between Kurstaki and aizawa strains and other insecticides. Neem oil is a great option to have around in your control regime.

let go of natural enemies

One thing that works to get rid of diamondback moths is to release natural enemies in your garden. The natural enemies kill large larvae, prepupas and pupae, so it is a safe and effective option for gardeners.

Some natural parasitic enemies left in the garden include: microplitis platella, diadegma insulare, and diadromous subtilicornis.

plant trap crops

You know that diamondback moths prefer plants in the cabbage family, so one control method is to try planting with trap crops. Based on what many gardeners note, this method appears to be highly effective. These pests enjoy white mustard and rape, both of which can be trap crops.

You can plant a row of trap crops between each other row of cabbages, or one trap crop at each corner of your raised beds. Once you see that the trap crop is full of pests, you can remove and burn it, which will kill those pests.

use sex pheromone traps

Since these pests have been around and studied for many decades, we know that sex pheromones are used by female adults to attract males, and that gardening companies make diamondback moth traps to plant in your garden. Huh.

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