Here are the details of the fruit fly trap demo we did recently. There are 2 simple traps – a sticky yellow one and a baiting liquid trap.
- Plastic sleeve – can be reused ziplock, document sleeve, etc
- Yellow paper/cardboard – if you don’t have any on hand, just get your kids to colour in a white piece of paper
- Horticultural glue or petroleum jelly
- String or old cable
- Cut paper/cardboard to be able to fit into plastic sleeve.
- If using document sleeve, seal end with some sticky tape to stop paper/cardboard from falling out.
- Tie a string using the hold on the document sleeve or if using ziplock back, pierce small hole on the top where it will not expose content.
- Hang the trap up before applying the horticultural glue or petroleum jelly on both sides. If you prefer, you can just do it on one side while the trap is lying flat on the table. Please be careful as the glue is very sticky and difficult to remove. It is therefore also a good idea to hang the trap where you won’t walk straight into it!
The horticultural glue is very sticky and should last at least a year unless you catch so much that it is completely covered or you get leaves and other materials stuck on it. You can buy the glue at nurseries or Bunnings. Here is the product info on Bunnings website. One tub will last you a long time; I’ve had mine for years and I use it for my fruit trees. If you don’t have the glue, just use petroleum jelly although this will need to be reapplied especially during hot days because petroleum jelly melts and slides off. But it is a cheap option, especially if you don’t have any glue on hand.
Liquid Baiting Trap
- Pet bottles – one for the main trap and a smaller one for the entrance. A clear one is best for the funnel so the insect will be more likely to enter. A clear one is also good for the main trap as it is easy to check what has been caught but plastic milk bottles are easier to cut and you can still see reasonably well. In the demo, I’ve used a 3l milk bottle with 1.25l rounded pet bottle.
- Knife and scissors for cutting
- Pencil/pen for marking
- String or old cable
- Liquid bait recipe (see below)
- Cut your smaller pet bottle about 5″ from the top so it is about the size of a funnel. I first make a small cut with a knife so I can insert my scissors to complete the cut.
- With the cut funnel, place it onto the main trap where the entrance will be and mark it. It should be about 2/3 of the way up the main trap bottle. Cut an ‘X’ where you’ve marked, slightly larger than the funnel top.
- Put funnel top into the cut ‘X’ of the main trap.
- Fill your main trap with baiting liquid about 1″ before the funnel opening.
- Put string/cable through the handle of the main trap or tie around the top if no handle, and hang it up securely on your tree between 1.5 – 2 m high; ideally at a height where the trap won’t knock your head when you’re under the tree!
Baiting liquid recipes I’ve tried (adjust according to the size of your main trap)
1 teaspoon vanilla essence
2 teaspoon cloudy ammonia
1/2 cup sugar
2 litres water
1 finely chopped apple
80 grams white sugar
1.5g dry brewer’s yeast (I’ve used instant yeast)
1 tsp vegemite
There are many more recipes available online which are a combination of these ingredients. Basically the liquid is attracting the fruit flies to a source of food for the larva (rotting fruit) or a protein source which they need before laying their eggs. You can mix and match the ingredients to see what works for you.
Here is a link to a few recipes by gardening gurus. Here is another DIY trap guide.
Please take note that these traps do not just target Queensland fruit flies. You can check your traps on a weekly basis to see what you have caught. I find this bit the most difficult as I hang the traps and forget about them 😛 If you can’t see from the outside, you will need to sieve the contents. Replace your baiting liquid if it dries out or loses potency. With the funnel trap design, it is less likely to dry out or get diluted by rain.
These DIY traps do not replace the monitoring traps that use lures. If you want to check if you have Queensland fruit flies in your garden, you should get lures which target them specifically. Please see http://www.biotrap.com.au for more details on specific products for Queensland fruit flies. We are not in any way affiliated to the company but we are organising to purchase traps in bulk to get them at more affordable prices for local home gardeners. If you are interested, please contact Claire.