The Garden of Eaden: ORGANIC CONTROL OF CODLING MOTH

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The codling moth is well known as a common and worldwide pest of apples. Unfortunately, this name is a little misleading as it is actually the caterpillar of the codling moth that does all the damage.

The adult moths are most active on warm nights during the months of June and July but even so, these moths are small and inconspicuous and are unlikely to be noticed. The female moths lay their eggs individually on the fruits and leaves of the apple tree which then hatch out into caterpillars a couple of weeks later. Once free of the egg, the codling moth caterpillar will immediately turn its attention to locating and tunnelling into the nearest developing fruit.

SYMPTOMSPut simply, the caterpillars tunnel extensively in to the flesh of maturing apples, making them inedible. Unfortunately, by the time that you realise your apple crop has codling moth the damage has – most probably - already been done.

CONTROLIt is difficult to control codling moth using chemicals because of the specific timing required to catch the caterpillars out in the open. Once the caterpillar has burrowed into the protective environment of a developing fruit they are unable to be controlled by suitable chemicals. Because of this, organic controls of codling moth on apples tend to be a far more effective method - especially when compared to wasteful and indiscriminate chemical spraying.

Perhaps the most common method of controlling codling moth caterpillars is to use pheromone traps, but these are only effective to a point! There are two types; the first has a pheromone that only attracts the male codling moth. This type of trap has a sticky base that prevents the male moth from flying away once it has landed. In turn this stops the trapped male from fertilising any female codling moths.

The second type is far more effective, attracting both male and female codling moths to the trap. They are lured by a pheromone which tricks them into thinking they are about to have a sexual encounter. However the trap is not there to prevent them from flying off - it has a more diabolical plan in store! The base of the trap is full of a virus that is known to kill the codling moth larvae. The moth leaves frustrated, but now it is full of the virus which it then passes on to other moths when it finally manages have a successful sexual encounter.

This eventually leads to the contamination of eggs laid by the virus infected female moths, as well as the site around them. The larvae are killed by eating the virus left on the redundant egg case or on nearby foliage.

Unfortunately, codling moth pheromone traps are not terribly effective in the grand scheme of things. In fact research has shown that one viral pheromone trap is only likely to infect 5% of the population of codling moths in an area of 1 hectare. Of course, if you only have the one tree in your garden, one trap may be all you require!