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Plantwise Factsheets for Farmers

Attract ants against white stem borer in coffee

Monochamus leuconotus (syn. Anthores leuconotus)

Recognize the problem

African coffee white stem borers (CWB) are dark-grey and white-grey beetles up to 3 cm long with long dark antennae. Adult beetles are difficult to find, but can sometimes be seen on young leaves and green twigs.

The 2 to 3 cm long pencil-thick young, called larvae, are white-yellowish. They feed inside the stem. You may find small holes in the bark, which lead to tunnels in the stem. Wood shavings, bark ridging (raised bark), dying of plant parts and wilting at dry weather indicate larvae damage


The beetles lay tiny eggs under the thick bark of old coffee stems, half a metre from the ground. They lay their eggs just before the short rain season (before August in the highlands and around July in the lowlands). Larvae hatch after 3 weeks and bore into the stem under the bark. This feeding reduces nutrient and water transport from the soil into the plant. Larvae are difficult to control because they are hidden in the stem. Adult beetles emerge through holes from the tree trunk at the onset of rains. Adult beetles do little damage.


  • Scout regularly for wood shavings and bark ridging between September and November in the northern zone, and between February and May in the southern highlands of Tanzania.
  • Search for holes on the trunks from 1 ft (30 cm) up to 3 ft (1 metre) above the ground.
  • Use strong wire to poke deep into the small holes on the trunk to kill larvae
  • Plug holes in the trunks with wool cotton plugs dipped in chlorpyrifos-based insecticides. This will kill the larvae in the tunnels. Wear gloves, because chlorpyrifos is also toxic to you.
  • Another method is to smear small wool cotton balls with hot animal fat from meat cooking.
Then stick 1 ball each right next to or below a larva entry hole on the trunk. Do not close the holes. If balls do not stick, fix them with thin rope
The fat attracts ants which will enter tunnels, and eat the coffee borer larvae in the trunk.
You can also just smear hot animal fat next to the holes without cotton balls. But this does not last so long as fatty cotton balls.

When using a pesticide, always wear protective clothing and follow the instructions on the product label, such as dosage, timing of application, and pre-harvest interval.

The recommendations in this factsheet are relevant to: Tanzania

Authors: Leonard Kiwelu, Edith Kija, Jubilant JN Mwangi, Mariam I. Mziray, Fredrick Magina
Tanzania Coffee Research Institute TACRI
tel: +255 784211663 email:
©CAB International. Published under a CC-BY-SA 4.0 licence.

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