Rice Stem Borer: Deadhearts, Whiteheads and How to Stop Them

Stem borers are among the five major rice insect pests of the country. A 2026 warning expected heavy attacks in Bicol, Central Luzon and Northern Mindanao in the early months of that year. So every palay farmer should know the signs, because a borer can hurt the crop from seedling to maturity.

How to Identify Rice Stem Borer

Pull the central shoot of a suspect tiller. If it comes out easily and the base is rotten or bored, you have a deadheart. Split the stem and look for the larva, tiny holes and frass, which is the powdery waste it leaves inside. Later, a panicle that is white and empty while the leaves are still green is a whitehead. Do not mix it up with the rice bug or with the rice whorl maggot, which only scrapes the leaves and does not tunnel the stem.

• The central shoot dries up and pulls out easily, which is a deadheart.
• A panicle turns white or pale and carries no filled grain, which is a whitehead.
• Tiny holes appear on the stem, with frass inside the tissue.
• Egg masses sit on the leaves of the seedbed and the young plants.
• Larvae in small tubes made of leaf wrappings float on the water and attach themselves to tillers.

How Rice Stem Borer Hurts Your Palay

Stem borers can destroy rice at any growth stage, from seedling to maturity. Deadhearts take away tillers that would have carried grain. Whiteheads take away the panicle itself, so the grain is lost completely.

We found no official percent yield loss for the Philippines, so we do not state one. Timing still matters. Rice hit during the vegetative and tillering stages can still recover, while a whitehead after flowering is lost for good. For the spray decision, use the light trap and the egg jar test below. Count the deadhearts and whiteheads in each lot every week, write them in your notes and compare season with season.

How to Control Rice Stem Borer

1. Prepare the land well. Plow and flood the field, and remove stubble and volunteer rice so the larvae have nowhere to wait.
2. Plant together with the farms around you. Synchronous planting with the right timing breaks the supply of tillers for the moths.
3. Check the seedlings before you pull them. If the leaves carry many egg masses, collect the eggs by hand before transplanting. Do not cut the leaf tops instead, because cut leaves let disease organisms in.
4. Handpick and destroy egg masses in the seedbed and at transplanting. Raise the irrigation water now and then to drown eggs laid on the lower part of the plant.
5. Split the nitrogen fertilizer into doses as recommended, and harvest at ground level so less stubble remains.
6. Protect the natural enemies. Many wasps, lady beetles, ground beetles, earwigs, spiders and dragonflies feed on eggs and larvae, so avoid early spraying. See our guide on integrated pest management.

When to Act: the Light Trap and the Egg Jar Test

When a Spray Makes Sense

Rice stem borers are best held down by resistant varieties and the steps above. If a spray is truly needed, ask your agricultural technician first, use only a product registered for rice, and never spray in the first 30 to 40 days after transplanting unless the pest is at outbreak level. Early sprays kill spiders and wasps and invite planthopper outbreaks. Let the jar test, not the look of the damage, make that call. Our guide on when to spray rice pests puts the stem borer next to the other rice pests.

The table stops at the ten best. 20 more on Philippine labels for it are older or broad chemistry. The Pest Finder in anee.io lists every one, crop by crop, with the products sold here.

Resistance. Striped stem borer in China now resists the diamides (IRAC 28) after years of heavy use. Do not use group 28 on two crops in a row. Switch with cartap (IRAC 14).

Keep It Out Next Season

• After harvest, plow and flood the field and cut stubble low, so the larvae resting in old stems die.
• Plant in the same weeks as your neighbors and keep a fallow gap, so the moths find no young tillers between crops.
• Pick egg masses off the seedlings before you pull them, and raise the water now and then to drown eggs laid low on the plant.
• Split the nitrogen into doses. Heavy early nitrogen gives soft, lush tillers that the moths prefer.
• Use a resistant or tolerant variety where your technician can supply one, and remove ratoons and volunteer rice.

Natural Enemies and Biological Help

• Egg wasps (Trichogramma, Telenomus, Tetrastichus) destroy many egg masses. Protect them by not spraying early.
• Where Trichogramma cards are sold, pin them in the field when the moths start laying.
• Spiders, lady beetles, ground beetles, earwigs and dragonflies eat the larvae and moths.

Not Sure What You Are Seeing?

Take a clear photo of the insect, the damage and the whole plant, then ask Anee, the smart farm technician in anee.io, in Tagalog or English. Anee tells you what it most likely is and what to do at the age of your crop. You can also put your scouting days on the cropping calendar, so the team knows when to walk the field.

Questions Farmers Ask About Rice Stem Borer