Many gardeners across the eastern two-thirds of the U.S. and southern Canada will start to notice damage from four lined plant bugs (Poecilocapsus lineatus) in mid to late spring. Appearing as tiny, round, sunken pockmarks on the foliage of such plants as forsythia, viburniums, Shasta daisies, lavender, oregano, geraniums, sage, mums, basil, peonies, mint, and many others, the damage is as distinctive as the insect itself.
Identifying four lined plant bugs
This true bug measures a quarter-inch in length at maturity, and both looks and acts like a little speed demon. Four, black longitudinal “racing stripes” grace the otherwise electric yellow-green wing covers of the adults (see feature photo). And with the ability to scuttle beneath foliage in a flash, these little buggers are difficult to spot and nearly impossible to capture.
Four lined plant bugs overwinter as eggs inserted into plant stems. Tiny, reddish-orange and black, rounded nymphs (see picture below) hatch in early spring and pass through five growth stages over the course of four to six weeks. As the young nymphs feed, little damage is evident, but as they reach maturity, you’ll start to notice the distinctive pockmarks they leave behind. Damage from the adult bugs is usually spotted in late May through June and perhaps into early July.
Organic control of four lined plant bugs
Fortunately, the adults feed for only one month before “finding love”, laying eggs, and then biting the dust. There is only one generation per year. Because the feeding period of the four lined plant bug is so brief – and the damage is largely aesthetic – control measures are seldom warranted, though insecticidal soap, horticultural oil, and neem oil are moderately successful against them, especially if the product comes in direct contact with the nymphs.
In my own garden, I don’t bother trying to control four lined plant bugs with any products. I simply prune or pinch off spoiled plant growth in early July, when the insects are gone. This encourages the growth of new foliage that will remain unaffected by this insect for the rest of the season.
For more information about managing pests in your garden, without turning to synthetic pesticides, check out the following articles:
- Our Guide to Managing Vegetable Garden Pests
- Preventing Pest Outbreaks
- Tips for Identifying Garden Pests
Have you spotted four lined plant bugs in your garden? Tell us about it in the comment section below.
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So weird that you posted this today. I was checking out my favorite nepeta and thought I saw a few of those tell-tale depressions. I thought naaahhh…too early. Gonna look again tomorrow
Extension office id’d the damage. They are on hardy chrysanthemum and japanese anemone.
Jessica, We have started seeing them on mums, cransbill geranium, evening primrose.
Thanks for the nice advice about not spraying anything and pruning the plants off in july, reduces the stress knowing the whole plant grows back again. And also not killing the short lived pest 🙂
My mint patch was infested with four line plant bugs and I was able to use a shop vac to remove hundreds of them. Spot checks only turn up 1 or 2 now which are easily managed by hand. For sturdier plants this seems like a great way to control this pest.
Great idea!
That is an awesome idea! Will try with my hand vac. They are on my purple beauty bush. Last year had them on May Knight Salvia and Russian Sage. I go out early morning or late evening with a cup filled with hot soapy water, sneak up on them and knock them off the branch before they disappear. They sure are fast at slipping away. Gotta be quick. Good luck all.
Love this idea! Can you please give a little more detail on how to use the shop vac to collect them? they have really done a number on my mint. Thanks!
Just go out mid-day and run the shop vac hose over, around, and down into the plant. The plant’s stems will get sucked into the hose, but when you lift the hose, they will come right out. But the bugs won’t.
Yes, I live north of Boston and I just noticed damage to my pineapple mint and see these bugs crawling all over. I am thankful they are not cucumber beetles which have infested my garden in the past. I will take your advice and trim the mint back in July and see what happens. Thanks!
Picking them off works for a small number of plants/area. But my garden is INFESTED with these bugs. Hardy geraniums, hydrangea (!), mint, salvias, butterfly bush, even cherry tomato plants! So picking them off is way out of my control at this time. Which of the products mentioned can I spray on the adults?
Very few products work on the adults, especially because they are so fast-moving. The nymphs are easier to control with horticultural oil or insecticidal soap.
They’ve been all over the mint, basil, peppers, and some ornamental flowers. Although there is quite a lot of damage prevalent, I’ve only been able to actually spot 2 beetles which I disposed by hand. Love the shop vac idea!
I have a heavily infested garden with these guys in everything: roses, weigala , hydrangeas, tomatoes, peppers, snapdragons, bleeding hearts, basil, bee balm, and my magnolia tree, etc.
Is there a way too help prevent them?
Cleaning up debris around susceptible in the autumn helps.
I read in an extension service article on them that the eggs are laid in the stems of many common shrubs like weigela, hydrangea, deutzia. in the fall, I am going to spray the stems of these shrubs (after leaves have fallen) with dormant oil spray. The idea is to smother the eggs. We’ll see if it helps.
They are decimating my basil and it is already mid July! If I spray with neem can I still eat the basil?
I think a better bet at this point is to knock them off your basil plants and then cover the plants with floating row cover. That would provide 100% control without the need to spray. Just make sure you don’t trap any four-lined plant bugs under the row cover.
They are destroying COMFREY and mullein, I didn’t know this was possible. The damage was mostly confined to my chocolate mint in the past, but this year they’re everywhere and on everything. They’ve been destroying my entire garden for a solid month plus. I’m on the coast of Maine – I don’t think I’m the only one having a tough year with these guys.
most interesting – I am north shore of Boston, just south of New Hampshire, and these guys are out of control this year! I also planted chocolate mint and they went crazy on it last year and I think the ensuing generation is all over my garden this spring. It must be their favorite mint or something.
My favorite product for most bugs is something called “Einstein Oil” which has Neem, garlic and other stuff and works really well. I mixed up a batch and sprayed and 90% of them are gone, will spray again in a week.
Normally I ignore these guys but it’s obvious there is some kind of population boom this spring that is doing more than cosmetic damage, some of the plants are getting devastated.
I have these bugs on my Montauk daisy, zucchini, Shasta daisy, oregano and a few others.
I’ve sprayed Neem oil and it seems to help.
I’m going to try trimming the damage.