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Traps free fruit farmers from moths and flies

Friday June 17 2016

Jane Wanja in her fruit farm in Murang'a County.

Jane Wanja displays a fruit pest trap protecting her orange fruits from pests, in her farm in Murang'a. Her oranges had developed symptoms caused by the False Codling Moth. PHOTO | RACHEL KIBUI | NATION MEDIA GROUP  

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The sun is overhead as I venture into Ithanga village in Murang’a County in search of fruit farmer John Kamuyu.

Undeterred by the scorching mid-day heat, Kamuyu, who grows oranges and mangoes, is on his five-acre orchard checking on traps that he uses to curb fruit flies and False Codling Moth (FCM), two big enemies of the fruits.

His mission, however, is interfered with by calls from farmers in the neighbourhood, who also grow the two fruits.

It is the orange peak season currently and many farmers are looking forward to handsome returns after taking care of their trees for the past one year.

But the two pests are a threat to their bid to change their fortunes, the reason why Kamuyu, a former primary school teacher, comes in handy.

“I must respond to this farmer, she has been calling me since morning,” Kamuyu says, offering me a chance to look at a trap hanging on an orange tree.


He uses the Bactrolure para-pheromone traps, which attract and trap male fruits flies into a special container.

“For the moths, one should use the Lnyfield traps. To eliminate both pests either from mangoes or oranges, you need the two traps on the farm,” adds Kamuyu who sells his fruits to a juice processing plant in Thika, making up to Sh100,000 a season.


The traps contain pheromones that attract the male fruit flies and moths. Once inside the trap, the insects get in contact with the killing agent and die.

“Fertilisation of eggs cannot take place when the male dies, which means the pest cannot multiply,” explains Kamuyu.

Soon, we are headed to the farm as Kamuyu responds to the distressed farmer.

Ten years after retiring, Kamuyu has taken the role of an agricultural officer by teaching other farmers how to eliminate the two pests.

Samuel Kagumba (right), an entomologist and
Samuel Kagumba (right), an entomologist and phytosanitary expert, with fruit farmers, John Kamuyu and Jane Wanja examine an orange infested with the pests. PHOTO | RACHEL KIBUI | NATION MEDIA GROUP

Our stop is at Jane Wanja’s orchard that hosts 200 trees. She is a sad farmer after her oranges developed symptoms that Kamuyu identifies as those caused by the FCM.

After listening to Jane, whose fruits were rotting and falling off the trees, despite using the trap, he realises that she failed to put up the Bactrolure para-pheromone chemical on time.

“Last season, I harvested 40 bags of oranges and sold each for Sh3,000 earning a total of Sh120,000,” says Jane. “This time round, I may not get anything.”

Fruit flies and FCM are major pests that attack oranges and mangoes.


However, the pests have other hosts as well. For example, Bactrocera species fruit flies prefers mangoes but can also attack melons, cucurbits, bananas, guava, loquats, matomoko, avocados and other wild fruits.

FCM has a wide host range that include oranges as the main, others a citrus fruits, macadamia, avocados, roses and capsicums.

Samuel Kagumba, an entomologist and phytosanitary expert, and the managing director at Farmtrack Consulting, says using the traps that go for Sh350 correctly is key to the success of fighting the two diseases.

“It is difficult to detect infestation of both pests for an ordinary farmer. Symptoms only show when it is too late, that is when fruits are mature. Therefore, do not to wait for the symptoms but rather use the traps for monitoring the numbers before the onset of season and increase the use traps when crop is in season to kill the pests.”

He notes that the appropriate time for the use of pheromone-based traps is at the onset of fruiting season.

“Remember, insects are always in our agricultural systems breeding on other hosts as they wait for the preferred host, the cultivated fruit. It’s advisable for farmers to use the traps for monitoring purposes.”


Get it quick


  • Fruit flies damage up to 80 per cent of a fruit, although this mainly depends on the locality, cultivar and season.
  • A female fruit fly can live for up to six months. During this period, it lays 500 to 800 eggs inside the fruit.
  • Eggs hatch in four days into larvae, which feeds on the fruit pulp and takes a week to mature.