Monday, 26 December 2011

Stink Bugs!

Our citrus trees are host to unwanted guests..

Stink bugs!! Eww!!

When we moved in this time last year, the poor lemon tree was covered in these things. I had never seen them before, but Rach identified them straight away as stink bugs. They are also known as Bronze Orange Bugs. They're back this year:

The above pic shows the mature stage bug. They have 3 stages: the first is green and quite difficult to spot. Next comes the immature yellow stage:

They feed on citrus trees by sticking their needle-like proboscis into young shoots and sucking out the juice.

Here are a couple of younger ones getting stuck in to some mandarins:

The adult stage reminds me of Darth Vader. "I find your lack of juice disturbing"

You can see Darth's sucker sticking into the shoot above.

When they are disturbed they give off a nasty stink - hence the name.

The fruit yield on my citrus trees is absolutely awful, and I think these little guys play a part in that.

So what's the plan to control them? I have tried a little bit of spraying with white oil. This seems to annoy the younger bugs, the mature ones don't seem too phased by it. I'm not too keen on spraying myself, as there are lots of other little critters around that are quite welcome - spiders, ladybugs, lacewings etc, and I don't want to frighten them away.

Picking them off and squashing them works ok - it's a bit yucky, and it stinks!

I do have a theory which I'm in the process of testing. I have 2 trees next to each other. When we got here under these trees was a carpet of weeds. I have been laying down newspaper and mulch as these things become available:

The left side tree is done, and I'm half way done the right side.

Now, when I'd mulched under one tree but not the other, I noticed that the stink bugs all but disappeared from the mulhed-under tree, and seemed to concentrate themselves on the one I hadn't mulched under.

So do they need a carpet of weeds under the tree to thrive? Perhaps the weeds steal nutrients from the trees and reduce their ability to fight off the bugs. 

I'll finish off the other tree as more newspaper becomes available. Funny how we used to swim in the stuff, but now I read my newspaper on an ithingy, so I keep an eye out for abandoned local papers when I walk the streets. The stink bug season will probably be over by the time it's finished, so I'll have to wait until next year to find out if my theory is right.

I don't mind if they don't disappear completely. I figure the trees can handle a few bugs and stay strong. 

Time will tell!

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