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Once the larvae begin feeding on plant roots, they limit nutrients and limit moisture. Early symptoms resemble other problems like root rot or drought, so it’s important to examine the rest of the plant before diagnosing white grubs.
Here’s how to identify and prevent white grubs from feeding on your plants.
Contents
Get to know blank worms
White grubs are the larval stage beetles of the Scarabaeidae family. These larvae usually feed on grass roots and hide among tall grass. It is also common to find them on the roots of corn, potatoes, carrots and some ornamental plants.
Blank worms were originally classified as members of the genus Phyllophage, but have been reclassified to various other species in the family Scarabaeidae. You will see blank worms that belong to the Cyclocephalus, PopilleAnd Ataenius genres, for example.
Regardless of classification, all blank worms generally look alike. They are usually cream and C-shaped when disturbed. They have reddish-brown heads and three pairs of short legs near their head. When fully mature, the larvae grow up to an inch long.
This distinct appearance is hard to miss once you see these larvae up close.
Some larvae are exotic (non-native) and some have developed resistance to pesticides. Some only appear in the evening or during the day, so finding the right control solution is even more difficult.
Stages of growth
Depending on the species, the larvae can have variable life cycles. For example, some go through several generations a year, and others live only two years in total. This adds to the challenge of finding the ideal treatment for these pests.
Although the larvae may have different life cycles, they go through the same stages of growth. First, the beetles lay eggs, then the larvae mature and pupate before becoming mature adult beetles.
For example, let’s look at Japanese beetles (popillia japonica). Adult Female Japanese beetles lay their eggs a few inches above the ground in the spring.
Within two weeks, the eggs hatch and the grubs search for nutrients in nearby plants. During the colder months, the larvae burrow and hibernate below the ground, where it is warm and protected.
Then they start feeding on the roots of the plant in the spring before becoming pupae for a few weeks. Finally, they transition into their mature adult form.
Monitoring the larvae is crucial in determining the proper treatment and getting rid of these pests.
So how can you tell you have blank worms?
Identify white grubs
As these grubs are very good at hiding, you should take the time to observe your garden and dig around the soil if you suspect grubs. Checking the soil is the easiest way to confirm that you have grubs.
Check the soil for a soft texture and watch out for wilting. These are two main signs of white worms, so you’ll have to dig a little deeper. The roots are the next place to check to see if there is any damage to the plant.
If you suspect grubs in your garden, remove the top layer of soil and look for creamy C-shaped grubs.
To save time, prioritize areas where pests live. Generally, the adults feed on the leaves of trees such as willows or ash trees. The larvae feed and hide in potatoes, corn, lawns, grasses and ornamentals.
White Grub Symptoms
Sometimes it’s not the presence of larvae that will alert you to an infestation, but the symptoms of your favorite plants.
A lack of root hairs is a sure sign of this pest, for example, because that is what they feed on. No root hairs cause stagnant growth and can lead to nutrient deficiency. When grubs continue to feed in large groups, they eventually destroy your plants.
Another tip is to monitor the feeding activity of the birds. Do you spot a group of birds eating around an area of your farm? Maybe that’s a sign they’ve found a big, juicy patch of grubs.
Another common symptom is wilting of implants. Remember that other causes of wilting can be temperature, lack of water or other diseases. To make sure your plants are getting the proper care, check each plant’s growing requirements.
Then, it’s time to go find the white grubs by digging in the ground.
If you have large patches of brown grass in your lawn, it’s probably worth removing some of the sod to look for grubs underneath. They are a very common cause of lawn browning.
Besides birds, other animals, such as skunks, also like to eat these little pests. Sometimes wildlife can alert us to problems before we see them ourselves!
White Grub Treatments
Typically, blank verse processing takes a multi-pronged approach.
As mentioned, birds love to feed on grubs. Encouraging birds to hang around and eat the larvae is one method to control this infestation. Hang feeders and place water sources to invite birds to your garden.
Some wasps and flies are also possible predators of white grubs. Thus, giving nature time to find and eliminate these pests is a treatment option. The downside to natural predators is that you have no control over the process except to create a healthy environment in your garden.
Neonicotinoids, a neurotoxin that affects insects, were once the go-to solution for eliminating white grubs. We now generally try to avoid neonicotinoids because we know they harm native bees and other beneficial insects, upsetting the natural environment in your garden.
Because you will never completely eliminate white grubs in your garden, the best approach is an organic approach.
Organic pesticides
Instead of applying chemical solutions to your soil, organic pesticides can be effective. For edible crops like potatoes or corn, stick to methods that won’t drench your crop with chemicals.
Beneficial nematodes are effective in treating white grubs preventively or when larvae are present.
Milky spore disease helps attack Japanese and other beetle larvae, but needs warm weather to work effectively.
Products containing Bacillus thuringiensis are also effective, especially when combined with other treatments.
Remember, timing is crucial. It is not useful to treat white grubs when it is not the right time in their life cycle and the white grubs are pupating or are already adults.
Maintain your lawn
Prevention is essential for a healthy lawn. Avoid cutting the grass too short in summer. Beetles love to lay their eggs in short grass, so mowing the lawn regularly attracts these pests instead of deterring them.
Cultivate a healthy living environment for your plants by removing weeds to discourage insects from coming. Remove debris and other dirt so there are fewer places for beetles to hide.
Watering heavily but infrequently ensures that the root system grows deep and strong to combat grub infestations. Shallow, excessive watering creates the ideal climate for larval growth, so avoid overwatering during the summer.
Check the top inch of soil every few days to see if it needs watering. This way you will avoid an accumulation of excess water and the growth of more larvae.
Simply remove the beetles if they land on your plants and keep them away from the crops. Drown beetles in soapy water to keep them from returning to your lawn.
Sampling to find grubs
If you are planting a new crop or want to monitor larval activity, you can take soil samples. Sampling should be done at the early stages of grub growth. In most areas, samples should be taken in August, but sample regularly before that, starting in the spring.
You can simply dig up a patch of dirt and look for larvae or buy a sample kit.
Follow the sampling steps set out by the manufacturer and watch for these common symptoms to tell if worms are present:
- Wilting
- Root damage
- discolored grass
Of course, if you see larvae or beetles, there is no need to sample. You know they are there. When you know what to look for, it’s easier to choose the right treatment method. But try several treatments if you don’t succeed the first time.
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