Hi I'm Cory Stanley with Utah State University Extension
and today is August 5, 2011.
And I'm here at the Kaysville research center
to talk to you about a pest that was found about this time last year
at this site: Drosophila suzukiia or the spotted winged drosophila,
as it is commonly called.
This is a vinegar fly that is related to the same flies that you will find
if you leave fruit out on the counter too long, you'll find them flying around,
but the difference between those flies and the spotted winged drosophila
is spotted winged drosophila have a serrated ovapositor
or a saw-like, egg-laying structure that allows them to lay eggs
in fruit that are still on the tree not ripe yet.
I'd like to show how we make the bait that we're going to use to attract
the spotted winged drosophila.
In Utah I'm recommending that we use a yeast and sugar solution,
although in other areas of the country, they're using apple cider vinegar.
I'm not recommending apple cider vinegar because for one,
it seems to evaporate very quickly in our climate,
and also it's not quite as attractive as the yeast solution
is to the spotted winged drosophila, and where we have very low populations,
we want to make sure we can detect the flies in small numbers.
This yeast and sugar solution is very easy to make.
For a homeowner, you can just use the little packets of yeast
that you find at the grocery store.
This is a quarter ounce of yeast.
For a grower, they'll want to us a larger amount
and make large batches of the bait, so they can buy the bricks of yeast.
And then just measure out multiples of quarter ounces
on a kitchen scale.
The recipe is pretty easy.
You're going to take 12 ounces of water which is a cup and a half.
You'll wanna make sure it's warm because it's easier to mix.
You'll add one packet of active dry yeast.
And four teaspoons of sugar.
The last thing that you'll want to add is a couple of drops
of unscented dishsoap.
The reason why you want to add the dishsoap is to break
the surface tension of the liquid that's inside the trap.
Otherwise, when a fly enters the trap it can just land
on top of the liquid and then fly away.
But when you add the dishsoap, it breaks that surface tension
and they will become trapped in the liquid.
So you just mix this up,
and once you have mixed very well
then you'll add it to whatever trap you've chosen to use.
Now just add about an inch to an inch and a half to your trap.
And you're ready to hang it in your fruit tree.
I want to discuss with you some of the different trap
options that are available to you.
There are commercial traps available.
They come in a two pack, and currently you can find them online
for about $10 for the two pack.
They look like this and you just hang them from the tree
with your lore in the bottom.
These are great, but you don't have to buy them online.
You can make some traps of your own at home from pretty easily accessible items.
This is a trap that's made from a drink cup with a lid on it.
A trap made from a deli cup.
(woman) And here's a trap that we've made from a peanut butter jar.
All of these traps have in common are they're plastic.
The stiffer the plastic the better.
And then we've just drilled holes in the side. Eighth on an inch holes.
And then created a hanger. You can use a wire hanger,
or as you see we've used zip ties on this or string.
Whatever suits your purposes and is easily accessible to you.
These traps are a little different in that they have a mesh top.
So you can drill the holes in the top of the lid
or you can create a mesh top. This is just glued in place with hot glue.
The difference is that if you use the holes in the top,
you'll want to create some sort of roof—this just a paper roof on this—
to keep the rain out so that your lore doesn't get full of rain
and overflow the container.
The advantage to having the holes in the top—and this is important for
commercial growers—is this is one that I used for my research.
It's got the holes in the top.
And then we're able to unscrew the bottom and carry it away
with the lid on and it won't spill.
So, that's really nice if you're going to be doing a lot of these,
and you want to screen through them at a site distant from
where they're hung in the trees.
The other advantage to having the holes in the top
is just if you have them in the sides, you need to be careful that you
don't spill them as you are manipulating them.
One other note about having the holes in the side,
if you have the holes in the side, remember to leave some space
where they're aren't holes so that you can pour the contents out
without it pouring through the holes.
So now we're going to hang the trap that we created.
This particular trap has the holes in the top, so it needs a roof
to keep the rain out.
This is the plastic container that the bait we created is in.
This is just that yeast-sugar solution we made earlier.
What I'm going to do is I'm just going to pick a shady spot
in the tree, up in the canopy.
And I'm going to hang the top up and make sure it's tied securely.
Now I can remove the lid from the container of bait,
and screw this on.
And I'll leave this up here for a week.
And in a week I'll come back and I'll just swap out for some fresh bait.
And I'll take the bait full of flies and look through it
for Drosophil suzukii or spotted winged drosophila.
Now we've brought this in from the orchard.
This has been sitting out for a week.
You don't want to leave you trap out on your tree for longer than a week
because this yeast and sugar will be pretty smelly
and you don't want to have to deal with that.
It will be much to too ripe for you to work with.
Just open this up and you're going to use a strainer
which has a very fine mesh.
Just any strainer you can find at a cooking supply or grocery store will work,
as long as the mesh is fine enough that the flies can't slip through it.
Pour the contents through the strainer.
If you have a lot of flies, you'll want not add them all at once.
So maybe just pour half the contents at a time.
Rinse out your container to make sure that you've got all the flies and insects.
Now at this point, many people would just pour your flies into a dish
with some water to look at it.
But I've found that you're a lot less likely to lose flies
and it's a lot easier to look at if you just use the strainer
and leave them in the strainer.
You have two dishes of water here. Cold water is a little less cloudy,
so I've used cold water.
The first one I'm just going kind of rinse any excess yeast off the flies.
And then the second dish I'll very slowly dip this strainer in the water,
and it causes the flies to float on the surface of the water.
Once your flies are floating on the surface,
you can look at them to see if there are any spotted winged drosophila in there.
If they're not all floating right from the beginning,
just lift it out and very slowly dip it in again.
Now I use a hand lense.
This particular one is a 20 by hand lense that I just bought on the internet.
This one has a light, which I really like.
It cost me about $5, but you don't have to have the light
if you have a well-lit room.
Then you can just look at all of the flies that you see in there,
and look for the ones that look like vinegar flies or drosophila.
And then examine them to see if they have the serrated ovapositor
that we're worried about or, in the case of the males, a spot on the wings.
If you do find one that you're suspicious about,
you can always pull it out, put it on a dish,
add a little bit of water so it's still floating,
and look at it more closely.
As you're looking through the contents of your traps,
you'll find a lot of flies, and you're going to get a lot of flies
that may look supicious.
There are a lot of flies out there that have spots on their wings
and there will be a lot of vinegar flies in the traps.
Things you're specifically looking for are in the case of males, spots on the wings.
A single spot to be specific on each wing; here towards the end of the wing,
and that will identify the male spotted winged drosophila from any other
spotted wing fly that you may find.
Also, for the females, although you'll find other drosophila
or vinegar flies that look very similar,
the things that you're going to want to look for are
a ovapositor that is very strongly serrated.
This is a very distinct structure and although these are small flies,
Once you've seen this structure, it's very large and very distinct.
There are other flies that have pretty interesting looking ovapositors,
but they're not going to have the same serration.
Another thing that you can look for, the drosophila have bands of dark
across the backside, but for spotted winged drosophila,
these bands are continous.
In some other species, the bands are not continous,
but if you find, especially in the case of the females,
which can be sometimes hard to identify, if you find a fly that has
an unusual looking ovapositor, maybe even a serrated ovapositor,
but it does not have continous bands across its backside,
then it's not a spotted winged drosphila.
If you find a fly that you think may be spotted winged drosophila,
and you need to have it's identity verified,
you can contact your county extension agent for further instructions,
or you can visit our website.
On our website we have instructions on how you can submit
a sample to the Utah Plant Pest Diagnostic lab,
and they'd be happy to identify the fly for you.
Also, they can give you, if it does turn out to be spotted winged drosophila,
they can give you some instructions on how you should proceed
to control the pest.