To control fruitflies, a spray with a pyrethrum solution can be used. It will kill bees if they are sprayed directly, but it does not leave poisonous residues. The best time to use it is in the evenings (after 6 pm) most of the bees are back in their hives.
There is a product commercially available called Flower-DS® (available at the Hygrotech Company, contact-addresses below). This product is made of natural pyrethrum and is acceptable in organic certified systems. Artificial pyrethroids will work as well if you are not concerned about organic certification, but they are stronger and will leave residues on the fruits and leaves, which are poisonous to other animals, to useful insects and to humans.
- Precautions: Be careful to spray late in the evening. Follow the spraying instructions. Wear masks and skin protection. All insect poisons are also poisonous to humans even if coming from natural sources.
- Frequency of spraying: Start shortly after beginning of flowering, and repeat approx every 5 days or according to counts.
- Please check the insect trap information to count your fly population. If no flies are trapped - there is no need to spray.
Frequent applications of neem can keep fruit fly attack to a minimum.
For more information on neem click here.
Fruit fly trap (Lynfield or bucket trap)
The Lynfield trap is cheap and easy to make. It is made of a cylindrical plastic container with 4 holes evenly spaced on its sides, a lid, a wire hanger and a bait basket (if it is to be used with a dry attractant). Similar traps can be made locally using 'Kimbo' or 'Blue Band' tubs or similar plastic containers or plastic bottles.
They can be used with either specific attractants such as methyl eugenol or food baits such as protein hydrolysates or yeast or a peace of fruit (banana, mango). Also vinegar is a very good attractant. (Methyl eugenol attracts males of Bactrocera species and of a few Dacus species). Food baits attract both males and female fruit flies, they are not species specific, and also attract other insects, including natural enemies.
Several types of commercial fruit fly baits exist but are not locally available or registered.
Use food baits that attract a whole range of fruit fly species in the orchard such as protein hydrolysate (Nulure®, Buminal®, Solbait®). An alternative is waste brewers' yeast at a rate of 45 ml per litre water. Use about 250 ml of the mixture in each trap. Add one tablespoonful of borax (di-sodium tetraborate) to each trap to prevent rotting of the flies caught.
A simple fruit fly trap is made as follows:
- Take a plastic bottle
- As bait, use 1/2 cup vinegar, mix with water
- Add 4-6 drops liquid dish soap (it heavies down the wings and the fruit flies drown), do not stir
- Then take a pen or pencil and poke 4 to 5 holes in the plastic, just big enough for a fruit fly to fit into, about 7mm. Once a fruit fly crawls in, it cannot get out. You would think they would just fly back out through the holes, but they will not! If you see fruit flies crawling around on the surface of your plastic container but not going inside, make the holes larger
- Hang the bottle in an area where you have seen most fruit flies. Depending on the amount of fruit flies you have, you can expect to start seeing the bottle fill up within just a few hours.
|Homemade fruit fly trap
|© A.M.Varela, icipe
|Fruit fly trap
|© A.M. Varela and A.A. Seif, icipe
The trap is filled with bait and hanged on the tree about 2 to 4 m above the ground within the canopy layer, in a semi-shaded spots, preferably in the upwind part of the canopy. The trap should be hanged in such a manner that branches and leaves are nearby, but not touching the trap. Traps should be hanged 10 to 50m apart, depending on the bait used. Collect catches weekly and sieve them.
Bagging prevents fruit flies from laying eggs on the fruits. In addition, the bag provides physical protection from mechanical injuries (scars and scratches). Although laborious, it is cheap, safe, and gives a more reliable estimate of the projected harvest. Bagging not only protects fruit from fruit fly damage but protect the fruit from physical damage improving the market appearance of fruits. However, it is only practicable on small trees.
How to make a bag?
Cut old newspapers measuring 15 x 22 cm or 12.5 x 27.5 cm for mango and for fruits of similar size. Double the layers, as single layers break apart easily. Fold and sew or staple the sides and bottom of the sheets to make a rectangular bag.
How to bag a fruit?
Blow in the bag to inflate it. Remove some of the fruits, leaving one on each cluster. Insert one fruit per bag then close the bag using coconut midrib or firmly tie top end of bag with string or wire. Push the bottom of the bag upwards to prevent fruit from touching the bag. Use a ladder to reach as many fruits as possible. Secure the ladder firmly on the ground and for bigger and higher fruits trees, secure or tie the ladder firmly on big branches.
|Mango fruit bagging in an orchard in Kenya to prevent infestation by fruit flies.
|© M. K. Billah, icipe
Bagging works well with melon, bitter gourd, mango, guava, star fruit, and banana. Whole banana bunches may be bagged inside banana leaves. Start bagging the mango fruit 55 to 60 days from flower bloom or when the fruits are about the size of a chicken egg.
When using plastic bags, open the bottom or cut a few small holes to allow moisture to dry up. Moisture trapped in the plastic bags damages and/or promotes fungal and bacterial growth that can cause diseases. Plastic also overheats the fruit. Bags made of dried plant leaves are good alternatives to plastic.
Remove the bags during harvest and dispose of them properly.