The placement of hundreds of homemade olive fruit fly traps is the best solution the one available to organic olive farmers to control the olive fly. In this publication, we will show you everything you need to know about olive fly traps: when to put them, how to do them, attractants used…
Currently, mass trapping is widely used in traditional and intensive olive groves, since it allows to reduce the intensity of this important olive pest. it usually saves on the number of necessary treatments with insecticides.
Within the olive fly traps, the homemade ones are the most used. Within these, the use of Olipe-type traps is the most common for fly control.
Olipe type Homemade traps
Olive-type traps are very effective and represent considerable savings for the farmer. In addition, they allow us to recycle plastic bottles to give them a new use.
The cost of manufacturing this type of homemade traps is mainly the time spent, being able to prepare about 200 bottles a day with proper handling. If we evaluate the costs and value the time invested, I estimate that its manufacture can be around 0.50 euros per unit.
On the other hand, if we are going to buy olive fly traps, the prices we usually find are between 3 and 6 euros per unit. Although there are more sophisticated traps designed by large companies, the excellent performance, ease and low manufacturing cost of the Olipe trap make it the most widely used.
Personally, trapping with plastic bottles seems more respectful and productive than using other techniques such as installing yellow strips with glue. Sometimes counterproductive, since it is common to find habitual predators of the fly trapped.
We owe the idea of these traps to the ingenuity of a member of the Cooperativa Olivarera Los Pedroches in Córdoba. The initial idea was optimized by the technical department of the cooperative through different tests and prototypes. In addition, studies were carried out comparing its effectiveness with other higher-cost commercial traps, demonstrating high efficiency at a lower cost.
In case you don’t have time to make them, buying olive fly traps is not expensive either and is a more profitable option than leaving the olive grove unprotected.
How do you make bottle fly traps?
To make Olipe traps for the olive tree fly at home, first of all we will need to save plastic bottles. We can use bottles between 1 and 2.5 liters in volume, preferably transparent, although colored bottles also work. Bottles for Fanta, Coca Cola and other soft drinks are especially resistant, making their use very interesting.
In the case of lemon Fanta bottles, the yellow color of the label will help us to improve the effectiveness of the trap.
Then, to hang the trap we will use rope or wire of about 60-70 cm, in case of using rope I recommend the ones used for packing due to its high resistance, although we must tie the ends to prevent it from fraying..
To somewhat increase the effectiveness of the trap we can surround the area where we will make the holes with yellow adhesive tape since this color attracts the fly.
Finally, the thickness of the holes of the trap, this must be large enough to let the fly pass through and avoid as far as possible the capture of potential predators, To do this, 4-5 5-mm holes are made in the upper third of the bottle. These holes can be easily made by heating a 3-4 mm metal tool on a stove, the chainsaw sharpening files or a punch can be useful for this task.
To make refilling the bottles easier, I like to make one of the holes a bit larger so that it fits through the tip of the spray lance.
Although it seems obvious that the bottles have to be put with a cap, there are people who remove the caps from the bottle. The fly enters the bottle and tends to climb to the top, after a while it ends up fainting and falling into the water where it drowns. In case there is no liquid at the bottom, you can also end up dying exhausted or dehydrated. If we remove the stopper we facilitate the exit of the fly and we will only be able to catch one that has the”bad luck”of falling into the water.
When to set olive fly traps?
To decide when to set the olive fly traps we must control the activity of this insect in our area.
Although the fly does not start spawning until the olive bone hardens. It is good to install the homemade traps before the bone hardens, in order to trap and eliminate Bactrocera oleae specimens. In our area this happens around the beginning of July, so we set the traps in June. However, this moment varies depending on the area and could be anticipated or delayed due to the weather. Thus, we can establish a good time to start setting the traps in the olive trees is between May and July.
During this time, the attractiveness of the fly attractant does not compete with the attraction of the olives, showing great effectiveness.
We must take into account that mass trapping is an interesting way to reduce the initial populations of the olive fly. Due to the exponential growth of the pest. It is especially interesting to control the first generations so that the presence of the fly is low and does not cause damage to the final olive harvest. Therefore, trapping the olive fly must be carried out preventively.
What attractant to use for the olive fly?
There are different attractants for the olive fly. Among the common attractants used are water-soluble diammonium phosphate, hydrolyzed proteins and vinegar.
In our case, we have observed that leaving the homemade traps in the olive trees from one year to the next, they continue to maintain a certain attractive power. This happens when the proteins of the insects trapped during the previous year break down. Thus, once specimens trapped in the bottles begin to be detected, we begin to fill them with water and attractant.
Diammonium phosphate for trapping in olive trees
Diammonium phosphate diluted at % has the advantage of being a fairly selective, economical and transparent attractant when dissolved in water, an interesting aspect to control the number of captures in the bottles. Due to these characteristics, it is currently one of the most used attractants, and it is common to find them for sale together with commercial traps.
Because it is a fertilizer and it can spill onto the ground when filling bottles, its use in organic farming was temporarily prohibited.
Vinegar fly traps
The use of homemade olive fruit fly traps with wine vinegar is another option, in my opinion with greater attracting capacity, although somewhat less selective and more expensive, being common to find a wide variety of flies. In our case, we usually use the dregs of the pitarra once vinegared, being very effective. To fill the vinegar traps, mix 1/3 vinegar with 2/3 water.
Hydrolyzed proteins have traditionally been widely used for fly bait together with insecticides to control this pest. Its dissolution with water is also effective for attracting flies of different species ( olive tree, cherry tree, fruit…) to the traps. However, due to the dark color it is more difficult to check the number of captures.
Sex attractants such as DELTASAN® are a good solution for pest monitoring. They are very effective in controlling the presence of flies. However, due to their cost and the fact that they only attract males, they are not recommended for mass trapping.
Where to place the olive traps?
Specialists recommend placing the traps on the south face of the olive trees and around 1.5 meters high. However, this is not something that is very appreciable. Also observing a good number of captures in traps located on the north face of the olive tree. Personally, I like to place the traps in a place where they are easy to locate and refill, preferably facing south but not too complicated.
In the case of multivarietal olive groves, their placement in the varieties of olives helps to increase the effectiveness of the traps ( Cornicabra, Verdial, Gordal Sevillana…).
How many traps should I place?
Logically, the greater the number of traps, the greater the probability of capturing flies. However, we will have to work more to place and maintain the traps, it is considered that between 25 and 100 traps per ha is a good amount. More than 100 traps would hardly allow us to improve the capture results and instead would increase our work in an unproductive way.
You already know how to make traps with bottles for the olive fruit fly and when and how to use them, surely you may also be interested in several of our publications:
Which fertilizer is best for the olive tree?
How many kilos of olives can an olive tree produce?
Factors of influence on olive yield.
We have translated the information on our website from Spanish to English. Please note that some words may have had their meaning altered during translation.