White grub in sugarcane and groundnut: how to identify and control it

Photo at the top: A white grub (scarab beetle larva) in the soil: creamy white body, brown head, legs near the head and a dark, swollen rear end, Photo: Ryan Hodnett, CC BY-SA 4.0

Quick answer

White grub is the fat, C-shaped, creamy white larva of a brown beetle. It lives in the soil and eats roots, so sugarcane, groundnut, maize, chilli and soybean plants turn yellow, wilt and die in patches. Control it with deep summer ploughing, beetle collection after the first rains, and a label-approved soil drench or seed treatment.

How to identify white grub

In Hindi the pest is called safed lat or gidar, and in Telugu veru purugu (root worm). In India the main species are Holotrichia serrata and Holotrichia consanguinea. In sugarcane, Leucopholis lepidophora is also found. You rarely see the grub on the plant. Dig around the roots of a wilting plant and look in the soil.

• Egg: white, almost round, laid in the soil a few centimetres deep.
• Grub (larva): fleshy and bent into a "C" shape. The body is creamy white and the head is brown or yellowish brown. It has three pairs of legs near the head. The rear end is swollen and looks dark, because the soil it has eaten shows through the skin.
• Pupa: formed deeper in the soil, inside a small earthen cell.
• Adult beetle: dark brown or reddish brown, about 2 cm long. The wing covers do not fully cover the abdomen. Beetles hide in the soil by day and fly out at dusk.

Damage signs

• Plants turn pale yellow and wilt, first in small patches, then in larger ones.
• Wilted plants come out of the soil easily. The tap root and fine roots are eaten away.
• In groundnut, the grubs also eat the pods.
• In sugarcane, the leaves turn yellow, the crown dries and affected canes come off easily.
• At night, beetles eat the leaves of trees near the field, such as neem, ber (jujube) and banyan. Heavy feeding can strip a tree.

Look-alikes and how to tell them apart

• Termites (white ants): also eat roots and cause wilting in patches. But you find many small, pale insects and mud tunnels, not one fat C-shaped grub. See our guide to termite control in field crops.
• Cutworms: grey or brown caterpillars that also curl into a "C" when touched. They cut young stems at ground level at night, so the cut plant falls over. They have extra legs along the body, and they are not white. See how to spot and control cutworms.
• Root and stem borers in sugarcane: these are caterpillars that tunnel inside the stem or the underground part of the cane. Grubs stay outside the cane, in the soil. See early shoot borer of sugarcane and the sugarcane root borer guide.
• Wilt diseases: the plant also wilts, but the roots are still there. With grubs, the roots are gone.

Life cycle and when it attacks

This pest has one generation a year. The beetles spend the dry months in the soil. TNAU (Tamil Nadu Agricultural University) notes that they come out of the soil after the first pre-monsoon or monsoon showers. They fly at dusk, mate and feed on tree leaves during the night, and go back into the soil before morning.

The females lay their eggs in the soil, about 5 to 8 cm deep. As TNAU describes it, one female lays 20 to 80 eggs and the eggs hatch in 9 to 11 days. Young grubs feed on organic matter for a few weeks, then move to the roots. They grow through three stages. The last, biggest stage does the most damage. TNAU notes that crop damage starts about one month after the mass emergence of beetles. Grown grubs then go deeper, pupate and stay in the soil as adults until the next rains.

Damage is worse in light, sandy soils and when the soil is dry. In the southern states, including Telangana and Andhra Pradesh, this pest is mostly a problem in sandy soils. So in kharif crops, watch closely from about a month after the first monsoon showers until the crop is well established.

Crops it attacks

White grub in sugarcane

Grubs eat the roots of young and grown cane. Leaves turn yellow and wilt, the crown dries, and the cane can be pulled out easily. Damage is worse when the soil is dry. TNAU advises not to keep a ratoon crop in a field that is badly infested.

Groundnut

Grubs eat the fine roots and the tap root, so plants wilt and die in patches. Later they also eat the pods. Groundnut on sandy soil in kharif is at high risk.

Maize

Grubs feed on the roots of young plants. Seedlings turn yellow, wilt and die. The Government of India IPM package for maize lists white grub as a pest of regional importance.

Chilli and soybean

Grubs eat the roots, so plants yellow, wilt and dry in patches. For other soybean pests, see the girdle beetle guide for soybean.

When to act (economic threshold)

The economic threshold is the pest level at which control starts to pay for itself. The Government of India's plant protection directorate (DPPQS) gives it as 1 grub per square metre in its IPM packages for groundnut and for maize. To check, dig out the soil of a 1 metre by 1 metre patch near wilting plants, down through the root zone, and count the grubs. Check a few such patches across the field.

For sugarcane, chilli and soybean we could not confirm a threshold from a recognised public source, so we do not give one here. In these crops, act on field history. If a field had grub damage last year, prepare it well and treat at planting or sowing.

White grub control without chemicals

• Deep summer ploughing: plough deep with the pre-monsoon showers. This brings grubs and pupae to the surface, where crows, mynas and other birds eat them. Pick up the grubs you see behind the plough and destroy them.
• Collect the beetles: right after the first rains, beetles gather on neem, ber and similar trees near the field. In the evening, shake the branches with a bright light nearby and collect and destroy the fallen beetles. DPPQS advises this right after the early rains. Do it together as a village where you can, so beetles from nearby fields are also caught.
• Trap trees: DPPQS suggests cutting back most host trees around the field and leaving a few favourite trees, so beetles gather there and are easier to collect.
• Light traps or bonfires: TNAU advises one light trap per hectare, or bonfires, when the summer showers come, to attract and kill the beetles.
• Timely sowing: DPPQS notes that sowing groundnut on time with the pre-monsoon showers avoids grub damage, where irrigation is available.
• Water on time: TNAU advises enough irrigation in fields with a grub history. When the soil is dry, grubs move into the root zone.
• Crop rotation: rotate with crops such as maize, sorghum or pearl millet, and avoid growing the same crop on a badly infested field year after year.
• Natural enemies: birds, parasitic wasps and fungal diseases of the grub keep numbers down. DPPQS also recommends entomopathogenic nematodes (tiny worms that infect and kill insect larvae) at one billion per acre against Holotrichia serrata in groundnut. Ask your Krishi Vigyan Kendra (KVK) where to get a registered product.

White grub insecticide: chemical control by crop

Only the products below have that crop and white grub on their official label. Doses are per acre, converted from the label's per-hectare dose. Use one product at a time. Do not mix products in one tank.

Sugarcane

Police Systemic and Contact Insecticide (fipronil 40% + imidacloprid 40% WG): label dose 177–202 g per acre in 400–510 L water. The label gives one application as a soil drench at the time of planting. Wait 296 days from treatment to harvest.

Groundnut

Police Systemic and Contact Insecticide: label dose 101–121 g per acre in 400 L water. As printed on the label, this is one spray at the seedling stage of groundnut. Wait 106 days before harvest. Read the leaflet for how to apply it, and ask your dealer or agriculture officer if anything is unclear.

Chilli

Police Systemic and Contact Insecticide: label dose 202 g per acre in 400 L water. The label lists white grubs and termites together on chilli, as a need-based application when the pest is seen. It does not say whether to spray or drench, so check the leaflet before use. Wait 3 days before harvest.

Soybean

Electron Insecticide+ Fungicide (azoxystrobin 2.5% + thiophanate methyl 11.25% + thiamethoxam 25% FS) is a seed treatment, not a spray. Label dose: 10 ml per kg seed (100 ml per 10 kg seed), one day before sowing or on the day of sowing. Put the seed in a polythene bag, pour the product on it and shake until all seeds are evenly coated. Dry the seed in shade and then sow. One application. The label covers this pest and termites as well as some seed and seedling diseases.

Maize

None of the products in our store has white grub on maize on its label, so we do not suggest one here. Use the non-chemical steps above, and ask your local agriculture officer or KVK for a product labelled for maize.

Police (two active ingredients) and Electron (three active ingredients) are ready-mixed products approved on the label. They are not tank mixes. Do not use a product on a crop that is not on its label.

Rotate to avoid resistance

Insecticides are grouped by how they work, using the IRAC group number (IRAC is the international Insecticide Resistance Action Committee). Pests that survive one product in a group can survive others in the same group. Fungicides have a similar system called FRAC groups.

Group	Active ingredient	Product in this article
IRAC 2B	Fipronil	One part of Police
IRAC 4A (neonicotinoids)	Imidacloprid, thiamethoxam	One part of Police and Electron
FRAC 11	Azoxystrobin	One part of Electron
FRAC 1	Thiophanate methyl	One part of Electron

Both products contain a group 4A insecticide. Grub control is usually one treatment a season, at planting or sowing. So the main way to slow resistance is to keep the field steps going every year and not depend on the chemical alone. If you also spray the same crop later for sucking pests, choose a product outside group 4A where you can.

Safety and waiting period

Product	Crop	Waiting period before harvest
Police Systemic and Contact Insecticide	Sugarcane	296 days
Police Systemic and Contact Insecticide	Groundnut	106 days
Police Systemic and Contact Insecticide	Chilli	3 days
Electron Insecticide+ Fungicide	Soybean (seed treatment)	No waiting period given on the label

• Police: do not enter the treated field for 48 hours after application, as the label states.
• Wear gloves, a mask, full-sleeve clothes and boots while mixing, drenching, spraying or treating seed. Do not eat, drink or smoke while you work. Wash well afterwards.
• Electron-treated seed turns pink-red. Never feed treated seed to birds or livestock, and never use it as food. Keep leftover treated seed away from food and feed.
• Bees and fish: both products are very toxic to honey bees and to fish and other water life. Do not apply when bees are active on flowers, and keep the product and washings away from ponds, canals and wells.
• Read the label and leaflet before use.

Frequently asked questions

Which white grub insecticide should I use?

Use one whose label lists your crop and white grub. In our store, Police Systemic and Contact Insecticide is labelled for sugarcane, groundnut and chilli, and Electron Insecticide+ Fungicide is a seed treatment for soybean. The doses are in the crop sections above.

How do I control white grub in sugarcane?

Plough deep in summer, collect beetles from nearby trees after the first rains, and keep the soil moist. In a field with a grub history, Police has a label dose of 177–202 g per acre in 400–510 L water as one soil drench at planting. Avoid a ratoon crop in a badly infested field.

When do white grub beetles come out?

Soon after the first good pre-monsoon or monsoon rain. They come out at dusk and feed on trees at night. This short window is the right time to collect and destroy them, before they lay eggs.

Why are my groundnut plants drying in patches?

Pull out a dry plant and look at the roots. If the roots are eaten and you find a fat, C-shaped white larva in the soil, it is a grub. If you find many small, pale insects and mud tunnels, it is termites. If the roots are intact, it may be a wilt or root rot disease.

Can I control grubs without chemicals?

You can keep numbers low with summer ploughing, beetle collection as a village, light traps, timely sowing and irrigation. These steps work well only when all farmers in the area do them every year, because beetles fly between fields.

Related reading

• Termite control in field crops: how to identify and stop termites
• Cutworm control in corn (maize), groundnut and vegetables
• Early shoot borer of sugarcane: dead heart signs and control
• Root borer in sugarcane: signs and control
• Girdle beetle in soybean: signs and control
• All insecticides
• Products for chilli

Sources

• Tamil Nadu Agricultural University, TNAU Agritech Portal: Root grub of sugarcane
• Tamil Nadu Agricultural University, TNAU Agritech Portal: White grubs of groundnut
• Tamil Nadu Agricultural University, TNAU Agritech Portal: Pest management in organic groundnut (white grub life cycle)
• Directorate of Plant Protection, Quarantine and Storage (DPPQS), Government of India: Integrated Pest Management Package for Groundnut
• Directorate of Plant Protection, Quarantine and Storage (DPPQS), Government of India: Integrated Pest Management Package for Maize
• Insecticide Resistance Action Committee (IRAC): Mode of action classification
• Fungicide Resistance Action Committee (FRAC): FRAC code list
• Product labels and leaflets of Police Systemic and Contact Insecticide and Electron Insecticide+ Fungicide.