The olive fruit fly is the insect that causes the most damage to this crop. To fight this insect without using pesticides, and thus keep the olive tree as healthy as possible, it is important to start mass trapping before the olives reach the size of a chickpea.
Let’s see how.
ORGANISING THE MASS TRAPPING
In order to fight this enemy, one needs to know about it: the adults of the fly are very long-lived and resistant to low temperatures, which favours their survival and, consequently, their reproduction.
The fly pierces the fruit when the olive is the size of a chickpea, laying its eggs there. When the eggs hatch, the larvae begin to feed on the pulp, after a few days they fall to the ground and turn into adults: then the adults pair and the females lay eggs again. This process is very rapid, taking about twenty days: the olive fly can go through up to 6 generations a year (a number that varies depending on the area of reproduction), which is why it is advisable to keep traps in the field until late autumn.
Here are a couple of things to keep in mind when organising mass trapping.
- Preventing the attack of the fly by placing the traps a few weeks before the first generation flickers.
- Keeping traps in the field until autumn to ensure that even the latest generation adults get trapped.
- Checking the traps and keeping the baits active regularly.
WHEN AND WHERE TO PLACE THE TRAPS
The best time to place the traps is from June, when in some areas of our country it is already possible to counter fly attacks, limiting the use of insecticides (or avoiding them altogether, especially in small areas) by using the Tap Trap cap hung on olive trees, combined with a bait made from raw fish and ammonia.
HOW TO DEFEND EXTENSIVE OLIVE GROVES
Having many hectares of olive trees to protect, the most recommended agronomic techniques involve placing one trap per plant along the perimeter of the olive grove and then proceeding to place the traps in a chequerboard pattern (one plant on and one plant off) within the perimeter.
For large realities we suggest to start with about 50 traps placed on 45-50 olive trees, in order to get aware of the bait maintenance work required and to be able to assess it before setting hundreds of traps.
BAIT WITH AMMONIA
Here is how to use Tap Trap for the olive fruit fly..
- Put half a litre of water in a 1.5 litre plastic bottle and add a couple of sardines (or raw fish scraps). It is not yet time to use ammonia.
- Hook Tap Trap onto the bottle neck (see how).
- Hang Tap Trap on the plant at eye level.
MAINTENANCE WITH AMMONIA
The bait does not have to be replaced: this step is very important because, unlike baits for catching wasps and lepidoptera, it is necessary for the first captured flies to macerate inside the trap. The substances produced by the maceration of the insects are, in fact, highly attractive to the flies themselves and it is in this way that the trap ‘self-triggers’.
After 10-15 days, when the trap has started to catch flies, it’s time to add the ammonia and to proceed once a month as follows :
- Add ammonia (cleaning use, not scented) every 15-20 days, taking care not to throw away the captured insects, not even the fish.
- Always keep half a litre of bait in total: if necessary, empty a little liquid taking care not to throw the caught insects and fish.
- Put the trap back in place.
Ammonia is a substance that the olive fly searches for in nature, which is why it is important to add it to the initially prepared bait. This component, in fact, together with the fish protein, will make the trap very attractive to the olive fly.
- A couple of times a year, replace the bait completely and do it all over again.
- You can also use Vaso Trap (the jar trap) for flies: here’s how to.
Where to buy Tap Trap
- To find out which dealer is closest to you, please send an email a firstname.lastname@example.org, or fill out this form
This blog article was written and edited by
Roberto Carello and Maura Rizzo
All photos, unless otherwise indicated, are under a free licence for commercial use or Copyright Roberto Carello and Vanda Bellini.