A major problem up north is the Guava moth (Coscinoptycha improbana), found in Northland, Auckland, Waikato, and Coromandel.

Hosts of this caterpillar are Guava, Feijoa, loquats, peaches, citrus, quinces, macadamia, apples, and pears; quite non-selective in its preferences.

In Northland (wild) loquats are the fruit that hosts the caterpillars in late winter/spring, allowing the population to build up.

People are now harvesting feijoas that have tiny entrance/exit holes in the fruit, allowing fungi inside the fruit, brown flesh, and rot. You’ll also find the caterpillar’s tunnels inside.

Those caterpillars entered the feijoas when the fruit were still small but just starting to swell – well after flowering. This is interesting information when it comes to trying to control the little buggers spoiling your crop.

Currently there are no insecticides registered for the control of Guava moth; some people use “Success”, a rather good caterpillar killer (Yates) and “on the Organic side” of pesticides as a by-product of bacterial excrement.

Other folk use Neem Oil – regularly sprayed (every 7 days) on the developing fruit.

Both these control chemicals have limited effect – about 50%.

There are no biological control organisms in NZ (Predators, Parasitic wasps, natural Guava moth diseases, etc).

Pheromone traps (that trap the lusty males) do not reduce the infestation – they just alert us to the timing of the flight season.

“Attractants” such as vegemite etc., don’t work.

Light traps are useless in controlling guava moths – most moths (more than 90%!!) caught are native moths of no relevance to feijoas.

What we do know is that later-maturing varieties/fruit are usually less affected by this caterpillar, and fine netting draped over the tree after flowering (when the fruit is growing) stops the female moths getting near the developing fruit for oviposition (egg-laying).

Hygiene is another control technique: clean the soil underneath the trees from debris and old fruit!! Collect the infected fruit (Feijoa, peaches, loquats, citrus… everything!) and chuck it in the freezer for two days before composting. Alternatively, chuck in a large bucket filled with water for a few weeks – put a lid on that bucket, so no moths can fly out.

Then compost the old fruit.