Herbal Pests: The Four-Lined Plant Bug

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You can check out the Lady Lemon Verbena at her bloghttp://lemonverbenalady.blogspot.com.

I hope that wherever you may have an herb garden, you don’t have this herbal pest: the Poecilocapsus lineatus. This four-lined plant bug started my Penn State master gardening volunteer efforts over ten years ago. I was having damage on my herbs and had never heard of a pest that made the kind of damage I was seeing. So I took a specimen of the bug and the damage to my local nursery and was told I had slug damage. I remember it was a nice dry, hot summer and I couldn’t believe that slugs were the culprits.

So, I made a trip to the local book store and found The Organic Gardener’s Handbook of Natural Insect and Disease Control (Rodale Books, 1996), edited by Barbara W. Ellis and Fern Marshall Bradley. On Page 329, there was my pest–the four-lined plant bug. I learned it is a true bug, meaning it has two stages–nymph and adult–and only has one generation a season, thankfully. Their damage is not life threatening to your herbs, but you may think it is once they start feeding. They love members of the mint family: mint, oregano, sweet marjoram, lavender, savories, sage, hyssop, horehound, lemon balm, catnip, and even basil, rosemary and thyme! All of your favorites! (Ironically my favorite, lemon verbena, is not one that is favored.) 

The damage done to my oregano plant.
Photo by Nancy Heraud

My nymphs this year are red or black. They can also be yellow. The eggs are laid in the twigs of woody plants in the fall. The adults like to lay their eggs on forsythia, deutzia, dogwood and weigela. I have all of these plants in my garden! These are just some of the ornamentals they can be attracted to. The nymphs usually hatch in late April or early May when the forsythia is leafing out. The nymphs have piercing-sucking mouthparts feeding on tender new growth. 

 A favorite food for the four-lined plant bug–peppermint!
Photo by Nancy Heraud

The damage also looks like the leaves are shrivelled or burned.

My summer savory looks like it has been burned.
Photo by Nancy Heraud

Just today I was out in the garden and most of the nymphs have morphed into adults.

I’ve put the four-lined plant bug adult in a safe place!
Photo by Nancy Heraud

Controls include insecticidal soap (nymphs only), pyrethrins and piperonyl butoxide, a combination of rotenone and pyrethrins and Sevin (carbaryl). Personally, I like to squish both the nymphs and adults by hand, with gloves or without. Get the kids involved. I hope they will have fun spotting them and squishing them as well. The nymphs and adults tend to “run” over the edge of the leaf and drop to the ground, but it is very satisifying to squish them between two leaves. Fortunately at the end of June, they are gone for the season and you can cut back the damage for regrowth before the end of the growing season. Just keep squishing and the four-lined plant bug season will end early, I hope! You won’t even know they were around!

I hope you do not have this damage on your herbs, but if you do, remember that you can take appropriate action with my tips to protect your herbs! 

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