Stink bugs

The flat-bodied bronze orange bugs in the photos below are also known as stinkbugs because of the vile odour of the secretion they release when disturbed. These bugs can do a lot of damage to citrus trees as they suck sap from new shoots and flower stems, causing shoots to wither, and crop losses. The secretion is very caustic and can burn foliage. Stinkbugs are commonly seen on citrus trees from winter onwards where a prolonged dry spell has caused water stress.
The young nymphs are green, (about 6 mm long) and can be found in groups on the underside of leaves. As they grow to adults, they can reach 2.5 cm in length, and change in colour through grey-green, to orange or pink-orange, to almost black. Older nymphs and adults are more obvious, clinging in groups to upper surfaces of foliage.
No organic sprays or treatments seem to be effective for these pests. We have found the safest organic way to remove them is to don some goggles or sunglasses and some long rubber gloves (to avoid the secretion burning or staining your skin), and then use a stick to knock them into a fruit tin containing some methylated spirits. It is best to de-bug your tree/s before the weather becomes too warm as, on hot days, the bugs leave the foliage and congregate around the base of the tree. The bugs will die off in hot, dry weather but by then they will have done a lot of damage.
Some gardeners use a vacuum cleaner to remove stinkbugs, but this method is only practical if your cleaner uses disposable paper bags so that you can dispose of the critters in a sealed bag, and if your vacuum cleaner and extension leads are suitable for outdoor use.
In summer, have a look under citrus leaves for stinkbug eggs. The eggs are spherical and fairly large for insect eggs (3 mm), and they are laid in rows. Remove the leaves carrying eggs and dispose of them in a sealed bag.
To prevent future attacks, make sure your citrus trees receive adequate water and are mulched to keep soil moisture more consistent. Also check that soil pH is between 6 and 7, and that your trees have received adequate complete fertiliser for best pest resistance.

The Brisbane Insects website has a lot of photos of stinkbugs (a.k.a. bronze-orange bugs) at all stages of their life cycle, including one of their mating position, and a close-up of exactly which part of their body releases the vile liquid.


35 thoughts on “Stink bugs

  1. John on January 14, 2016 at 3:38 pm said:
    I have noticed the stink bugs on my orange tree all to the ground on really hot days say 37 and above, then at the end of the day they all crawl back up the trunk.
    Thank you John, its all about the timing….
    I used a blow torch with butan gas, I bought it from hardware shop. i have killed hundreds of these in less than 30 seconds. there is no chance for them to escape. i have done it twice in the last 3 weeks and now much better hardly any around.

    If there are too many of these pests to remove manually, the best time to treat them is when they collect at the base of trees in the heat of the day, which is when you should NOT use pest treatments. Denny has shown lateral thinking in solving the problem, without also killing beneficial insects that visit citrus trees. Clever. – Lyn

  2. No-one has mentioned this trick I have used. I use a spray bottle with beer…. Yes beer…. What a waste!, ….. but it slows them down enough so they can easily be picked off. Then I drop them in a bucket of metho.
    Thanks, Chris. That is definitely worth a try, but avoid spraying them when they are clustered at the base of the tree on hot days. Even a small amount of beer in soil kills earthworms that work so hard to improve our garden soils. – Lyn

  3. Following up on the entry above. I suggested wearing wrap-around eyewear and I must underline that. You might think that normal spectacles would do the job; well they won’t. Also the small immature bugs are just as dangerous to the skin and eyes as the large dark ones. Next, you can now buy a can of insect spray with a long yellow tube outlet that allows you to target a bug without filling the air with insecticide. Of course if you have just one or two trees that are heavily infested each year you might ask yourself if you wouldn’t be better off without them! – Peter van Sommers
    Thanks, Peter – good advice. I presume you mean be better off without the trees that are repeatedly infested? However, pest infestation occurs when plants are stressed because they can’t uptake the elements they need to produce their own pest deterrents. It is understandable that plants may be water-stressed at the moment in areas that desperately need rain, but repeated infestations mean that you need to look at your soil pH, your watering or fertilising program, or whether you are trying to grow plants that are unsuited to your climate. – Lyn

  4. I am in too late to hand pick them off the trees – thousands of them. I did so later the spring, already too late then, and I got headache every time afterwards. So I am thinking either to prune my trees or use milk/oil/detergent or wait them to die in the hot summer (Will they really die if I wait?). I am desperate and worry my trees may die. What shall I do?
    It depends how hot is gets where you live, Li. If you are worried about your trees dying, you need to improve watering and/or fertilising and mulching of your citrus trees. Pests are attracted to stressed plants as healthy plants produce their own pest-deterrents, and to have thousands of these pests on your trees, they must be very stressed. If you do use a spray, Yates have an organic-registered spray ‘Citrus and Ornamental Spray’ which is said to be effective on bronze-orange bugs. Spray them when they are sheltering around the base of the trees as this will avoid killing ladybird larvae and avoid the problem of spraying foliage in hot weather. You will still have to wear goggles and protective clothing. – Lyn

  5. I ended up at the eye clinic in Sydney after a direct hit from a bronze citrus bug. I shall never tackle these insects again without wrap-around goggles. It is interesting how obsessive one can become, going after these bugs as soon as you see one or two, but the urge has to be controlled until you are properly prepared with gloves and goggles. Getting that strong alkaloid liquid directly in the eye is very educational! I was put completely out of action for twenty minutes, washing and washing it with water from a small liqueur glass (I couldn’t locate our little eye bath!) Many people recommend milk which may be marginally better. There seems to be two significant issues I should mention. First people say the ejected fluid (which can travel backwards from apertures on the sides of the bug a good part of a metre) is “caustic”. If you think this means strongly alkaline, you are on the right track because that is what it is. Not acid as we might expect from a bug on a citrus tree. I also think, though I am not sure, that the fluid is oily which would make simply washing with water less effective, and it would be good if some clued-up person could address that issue and maybe offer advice about the best washing procedure. From my recent experience don’t depend on nurses, pharmacists or even optometrists to know about any of these issues. If you deal with these bugs at all, clue yourself up, and above all, stop until you are dressed properly.

    Peter, you are correct in saying that virtually no information is available for the treatment to injuries from the citrus bug. This website Bronze-olive-bugs-on-my-citrus recommends using room temperature milk as a neutraliser, and repeating the treatment regularly over several days. Milk, cream, yoghurt and sour cream are all effective in neutralising the pain from chilli capsaicin if it is transferred to the eye, as water is not very effective. It is worthwhile also rubbing a dairy product into your hands after handling chillis. Milk may be a suitable neutraliser for citrus bug ‘juice’, too.
    However, anyone who has received an eye injury from the liquid from citrus bugs should see a doctor A.S.A.P. as the liquid can damage the eyeball. – Lyn

  6. Hello~ Lyn. I removed stinky bugs with my hands today before I read this page. I did not know they spray. Oh my gosh~ 🙁
    Thank God that I wear rubber gloves and plastic gloves top of it and long sleeved shirts, mask and hat. But forgot that safety glasses. What I done today is pick the stinky bugs and put them in the plastic bag and step on them to kill and then threw it in the bin. Do you think this is alright solution? And do I have to remove stinky bugs by hand until they disappear? I really don’t want to use chemical spray because don’t want to kill beneficial insects. what do I have to do help my poor citrus trees to become healthy again. Thank you very much for your help and really useful information.

    You haven’t said where you live so I don’t know how hot it gets in your area. It’s best to get rid of them the way you are doing it before they do too much damage and head for shelter around the base of trees as sprays are not very effective on these pests.
    As for helping your trees to become healthy again, a lot of gardeners do not realise that only stressed plants attract pests because healthy plants produce their own pest-deterrents. Sometimes stress is unavailable as during drought conditions but, as it says in the above post: “To prevent future attacks, make sure your citrus trees receive adequate water and are mulched to keep soil moisture more consistent. Also check that soil pH is between 6 and 7, and that your trees have received adequate complete fertiliser for best pest resistance.” – Lyn

  7. I have noticed the stink bugs on my orange tree all to the ground on really hot days say 37 and above, then at the end of the day they all crawl back up the trunk. It is at this point I use a plastic cricket bat to flatten as many as I can then hose the remains down. Does anybody know why they do this?
    They don’t like too much heat, John, and hot air rises. They instinctively know that the air will be cooler closer to the ground on hot days. As the temperature starts to fall, they return to the foliage. – Lyn

  8. Has anyone tried using a spray bottle full of chilli and garlic ? I am going to do it this week on my mum’s lemon tree and see what happens.

    Hi Therese, there have been no treatments discovered so far that kill these pests. What it will do, however, is get rid of the larvae of beneficial insects that are also found on citrus trees. – Lyn

  9. The sting bugs last year the destroyed my orange tree half went dead and also my mandarin tree the mandarins were dry and full off hole. I try commercial pest control chemical but no results. I tried with great success a with mixture or garlic , hot water and eucalyptus washing detergent and I hit them and are falling down . Easy every morning I go and check .When I find one or two I spay and are gone. The only thing is I worry when I go away for a while may be are coming back .
    Akis, your trees are very stressed if they are being severely attacked and the fruit is dry. I would be looking at correcting the stress by improving irrigation and fertilising. Happy trees produce their own pest-deterring pheromones. – Lyn

  10. I was removing the bugs by hand with the thin latex gloves, however, it seems that the orange stain has bled through making my right thumb and two fingers look like I have a very nasty smoking habit. Have tried to remove it but to no avail – any chance of a secret to getting it off the skin?
    Oh dear, Mark. Thanks for the warning about the latex gloves. I always wear those pink, silver-lined washing up gloves for those jobs and have not had that problem. You could try “Sard’s Soap’ from supermarkets. I’ve found that very good at removing various stains. After using it, wash your hands with a gentle soap and rinse well, as it can irritate some people’s skin (particularly if you have had to scrub your skin). – Lyn

  11. I use long scissors ….aim and cut them in half…even if they crawl away they’re finished …i find that if they get to spray a piece of fruit the fruit itself will also die 🙁 nasty bugs

    Egoitz, that is a very risky practice. Yes, they are nasty bugs but you need to get too close to them to cut them with scissors. Stinkbug spray is very caustic and can damage the surface of your eyes and burn your skin.
    Stinkbug Spray – immediate action: Flush eyes or sprayed skin with plenty of water to dilute the spray. If sprayed in the eye, also see your doctor as soon as possible. – Lyn

  12. I picked them off with rubber gloves as well and still got stained fingers. Funny thing is I did it a week earlier too and thought the stains were from flowers. Definitely double up on gloves next time or use tongs. I sprayed them with soapy water and threw in a bucket of soapy water which they didn’t like. The stain does disappear in about a week.

  13. I wish I had read about this earlier 🙁 My poor lemon tree has been decimated by stink bugs and now I am wondering if it will ever fruit again. Is there something I can do to help, it as it is quite established and previously bore lots of fruit? Thank you
    Sue, stressed citrus trees have this problem. See how you can improve watering or fertilising to prevent this occurring in future. – Lyn

  14. I have had the spray seep into my fingertips despite wearing gloves. There was no discomfort besides some temporary staining for a few days. The other day though I was sprayed on my arm. It stung immdiately and straight away I washed soapy water over it and 6 days later it still hurts and has gone very red and a very unpleasant itch attached to it. Scratch it, it hurts. Hate to think what the outcome would have been if it got me in the eyes.

    So far I’ve had an unsuccessful search for official first aid for stink bug burns. One article says that in India, they use milk to relieve the burning sensation from these bugs. (bronze olive bugs on my citrus). I found this interesting because milk products are also the antidote for the burning sensation from chilli, including in the eyes. Other sites commented that the spray is very acidic and one suggested a paste of baking soda. You could try these remedies and let us know if they work, otherwise all I can suggest is ‘Chemists’ Own Cream’ that is antiseptic, anaesthetic and anti-inflammatory. I use it regularly on my granddaughters for various, stings, burns and other injuries.– Lyn

  15. I brushed orange tree yesterday without noticing the Stink Bugs and got sprayed on the back of my hand, five or six spots about the size of a 5c piece. I didn’t notice until it started to sting. Washed the area well with soap but it’s still stinging and itchy this morning. Not nice at all. Glad they didn’t get me in the eye.

  16. Thank you for all the info, before looking as this site I used very hot water only and that did the trick. Was wondering if the dense discolouration on fingers (one disposable kitchen glove) from stink bugs was dangerous? Tried the eucalyptus oil as suggested, nothing significant! Tried the sards soap with old scotch brite and that was more successful. Thank you all
    Hi Carol, thank you for letting us know that the eucalyptus oil didn’t work. Although the stink bug discharge can burn your eyes, I don’t know that it is dangerous on your skin if you clean it off quickly. – Lyn

  17. Re Kate’s stained stink bug fingers.
    I use 2 pair nitrile rubber gloves. One pair doesn’t work but double gloved does. And eye protection too.
    I was looking for an organic spray but read here that sprays will knock off the good bugs too, so it seems it’s manual removal the best way to go.

    Thanks, Brendan. – Lyn

  18. @Kate Caddy I killed about 40 stink bugs yesterday, picking them off my oranges, limes and lemons. i also wore rubber kitchen gloves. Took them off an hour later to find my fingers a horrible burnt orange colour! Did the eucalyptus oil work? I’ll buy some tomorrow if it did. Luckily my fingers dont smell.
    i might try Bob’s trick and use tongs next time.

  19. i have 2 mandarin trees with about 100 stink bugs on it and me and my brother like to hit them off with a long stick but recently I got sprayed in the eye by the pesky things what should I do?
    Sorry to hear that you were target with stinkbug use. I think I mentioned in my article that you should wear goggles or sunglasses (wrap around style is best) and rubber gloves when removing this pest. – Lyn

  20. I use a pair of long-handled barbecue tongs to pick the bugs off and drop them in a bucket half-filled with water. They seem to drown quicker if the water has some detergent in it. I started doing this three years ago. We moved to a place that has a mandarin tree, and I didn’t notice the bugs until the underside of the leaves were almost completely covered with black adults. The next year I got to them earlier, when they were green, then orange, and didn’t see any black ones, but yesterday I got a fat black adult. The population is getting smaller, and the fruit crop has improved, but it might be a while before the bugs are eradicated.

  21. I just removed about 200 stink bugs from my much loved cumquat tree. I was wearing gardening gloves but didn’t realise that the stain was getting through until it was too late and now have deeply stained fingers. Does anyone have any suggestions how to remove or lighten the staining? At the moment I have to wear band-aids to cover the fingers when I go to work because they look so bad!

    Oh dear, Kate. I haven’t had this problem because I use a stick to knock them into the container. According to this post on Brisbane Insects, the orange stain on skin can last about a week. However, it also says that it was removed from clothes after washing several times with soap. I’d try using cotton wool to rub some eucalyptus oil into your fingers. This is a good general solvent and may loosen up the pigment in the stain so it can be washed off. For washing your fingers, I’d try a bar of Sard’s Wonder Soap. It is very good at removing stains, including ‘Mission Brown’ paint from white trousers. Thick rubber gloves may be best for future stink bug missions. Please let other readers know whether or not the Sard’s works. – Lyn
    P.S. It might be better to avoid hot water. I think I read somewhere that it sets protein stains.

  22. Congratulations Corinne, your harvest of stink bugs is truly impressive. It is not a good idea to fertilise during hot, dry periods, and the best time to fertilise citrus is just after harvesting when they begin a growth spurt. Just concentrate for now on giving your tree a regular, deep watering when the top cm of soil is dry. I hope and pray you have some very good rain soon. After harvest, give your tree a generous application of a complete organic fertiliser, a dusting of dolomite or Epsom Salts and, because it has had a pest infestation, a dose of seaweed extract tea to help it produce its own pest deterrents. In the meantime, don’t forget to remove the stink bug eggs from under the leaves.

  23. Thanks all. After reading your posts I finally declared war on our stink bugs using the simple ‘hot soapy water in a bucket’ method. I wore thick gardening gloves, a long sleeved shirt, enormous wrap around sunglasses and a floppy hat, and feeling suitably armoured up I just picked them off with my fingers and put them in the bucket. In the end I killed 108 big black adult ones and 2 small green young ones off one large myer lemon tree. I had been procrastinating about this task for over a year – the final straw was when they starting stinking out my son on his bowling run up in a game of backyard cricket! Not surprisingly, our poor lemon tree is looking a little worse for wear with quite a few yellow leaves, and some quite bare branches near the top of the tree. Having said that it is laden with large green lemons. I would welcome advice on how to coax my tree back to good health after this infestation. I was going to fertilise it but then thought it may not be the right time since we are still in the think of a long, hot dry canberra summer….

  24. Stink bug citrus beetles will drop like flies with my concoction of full fat milk cheap cooking oil and dish washing liquid. If anyone is interested email me and I can explain mixtures. It’s cheap, effective and kills even the adults in under 1 minute. I use it every year on my mandarins,lemon and orange trees.
    I can’t believe no one has mentioned this before. It’s a granny’s recipe that tried and tested, will also kill the biggest and meanest looking grasshoppers in under 2 minutes. Regards to all the home gardeners. Shane okeefe

    Hi Shane, thanks for your suggestion. However, I do not recommend sprays for these pests as anything that will kill the stink bugs will also kill the beneficial insects that consume masses of other pests in your garden. When you kill off predator insects you leave your garden vulnerable to further pest attacks.
    Also, cooking oil and dishwashing liquid can burn plant foliage, especially in hot, dry weather. The oil clogs the tiny holes that are essential for photosynthesis and respiration (conversion of carbon dioxide into energy for growth), and transpiration (which enables plants to maintain humidity around them). In a rare situation where you must use sprays, and you need a ‘spreader’ for the spray, you should use a potassium-based soap product, such as ‘Natrasoap’, which leaves no residue on plants and is also an effective pesticide for soft-shelled insects, including the nymphs of these pests. The safest place to spray them is when they shelter at the base of trees on hot days. But spray carefully, to avoid killing the good guys, too. – Lyn

  25. I have found that the bugs die even if you drop them into water – you don’t need meths etc. Also, as a first aid, I’ve found that when I’ve been sprayed (burned) in the eyes/nose, I have immediately grabbed a leaf of aloe vera and applied the gel which is fine for the eyes. Works straight away.

    My question is though, this year I have small white spots covering all the crops underneath and around the citrus trees as well as the citrus leaves and I was wondering whether this could be from the secretions of the bugs? I haven’t noticed it in previous years althought it is very dry in Lismore this year.

    Thanks for sharing Terry, about the water and aloe vera. Water is preferable if it works as it avoids having to dispose of the meths safely. I can’t say I’ve ever noticed white spots under the leaves and I can’t check our plants as we don’t have these pests now despite the prolonged dry weather. Are the spots flat? I mean they couldn’t be eggs, could they? Another possibility is powdery mildew – that is a common problem at the moment. Maybe other readers with stink bugs can confirm whether or not they are droppings. Anyone???

  26. Thank you Lyn, However, I am disappointed that there is no known organic treatment. I have just vacuumed them (with an old, now outdoor vacuum) from my ~10 citrus trees. That does work well & is extremely satisfying!!! You do get better at finding their hiding places. There seem to be hundreds on our trees. We used an insecticide last year, but they are back again now & I don’t want to use the insecticide again (we normally never use them). So vigilance seems to be the best method & then finding eggs.
    Our worst trees surprisingly, were the ones in the wetter part of the garden????

    Citrus trees need well-drained soil and constant ‘wet feet’ causes them stress which makes them susceptible to pest and disease attack. See if you can find a way to improve drainage around the trees, or grow something like nasturtiums under the trees to help soak up excess water in that area. P. S. Under-plantings of nasturtiums are said to also deter aphids. – Lyn

  27. Thanks Lyn, I know for a fact that they are not “hiding’ on the base of the tree as this is largely uncovered. There could be some in the foliage as it is a rather dense tree…..
    Over the last few weeks I have picked off a few more, say about 5 a week, but this week I have only seen 1 or 2 (could be the same one, I couldn’t reach it) so I am hopeful that I did get them all before they managed to lay (many) eggs. Hopefully we prevented them from mating too….. Do you know when the eggs can become visible? I’ll have to prune the tree this year so will clean it as well.

    I tried to get a photo of the eggs to show you, but no luck. The eggs are laid on the underside of leaves anytime from mid-summer to autumn. They are round, about 3mm in diameter, and laid in 4 rows. Each female lays up to 14 eggs. Young nymphs are usually found on the underside of lower leaves during winter, so the eggs are probably laid under lower leaves, too. – Lyn

  28. We have had them on our orange tree and I have gone at them with tongs and long-nosed pliers when they were still green and orange. We got most of them but there now are still a few black ones that “got away”.
    So the chances are they will have mated and laid eggs, do you know when these can be seen and removed?
    Also, do you know when the few remaining adults will die off?

    Chris, they lay eggs from mid-summer to autumn. The post above says they die off when temperatures are high and humidity is low. If you can’t see them now, they may be hiding around the base of the tree. – Lyn

  29. In the last month I have had a large amount of stink bugs on my orange tree .Rather than picking them off I use an old vaccuum cleaner with a disposable paper bag and suck the critters off. Then whilst the vac is still running I spray some insect spray into the nozzle to kill them. With the extension pole on I can reach all over the tree. This way I don’t risk getting any of their spray on me. Every few days I check for the odd one but this method seems to work quite well.-Sandra

  30. It is amazing, it’s almost like you knew I had a question. Last year I stayed home for 2 weeks in October while hubby and kids went to the UK to visit rellies. The whole time was spent picking stink bugs off my beloved orange tree, and I’m not joking – hours every day.

    This year I have not seen a single one, I’ve smelt them when the lawn mower goes under the tree but no sight at all. The only explanation can be as you suggested, adequate watering as we have had a lot of rain this year. Fascinating ( and a great relief)

  31. I have used a similar organic approach, however instead of metho I use hot soapy water. It seams to help the bugs drown. Then I wrap the dead bugs in newspaper and throw them in the sulo bin to have them removed from my property because I heard that if I put them in the compost they mave still have eggs on them to reproduce. Is this likely?
    It is quite possible that they might contain viable eggs Tamara. Pests should never be put into compost. Hot soapy water would be a suitable alternative to metho, if it kills the bugs. – Lyn

  32. What is the first aid to stink bug secretion to the eye?
    I can’t find anything about specific treatments for this problem Helen, but I would immediately flush the eye with lots of tepid water to dilute the secretion. If there is any resulting inflammation, probably your doctor will be able to prescribe suitable drops or ointment to repair the damage. It is very wise to wear sunglasses or goggles when treating pest problems as there are several pests that release secretions as a form of defense. Hope this helps. – Lyn

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