Pest of the Week - Four-lined Plant Bug

Recently, the four-lined plant bug was spotted during an IPM session at the Burlington County Community Agricultural Center.  The four-lined plant bug, Poecilocapus lineatus which is easily identified by the four black strips running down its back, has a wide range of hosts including: fruits, vegetables, flowers, herbs, and cucurbits. The associated damage consists of spots that look similar to fungal disease spot and can be misidentified as such.  

Adult Four-Lined Plant Bug - Courtesy Purdue University

Natural History

During the fall, the banana shaped eggs are laid at right angles in vertical slits measuring 2 to 3 in. along the plant's stem. They are usually not laid individually but instead are laid in groups of six or more. The eggs will over winter and hatch in May or late June just after the plant's foliage emerge. 

Nymphs will remain near their hatching site and feed on the upper side of leaves removing the plant's chlorophyll. After advancing through five molts in a period of about six weeks, the four-lined plant bug will have matured to an adult form. Adults will feed, moving from plant to plant, for approximately one month before mating; adults will not overwinter, and there is only one generation per year.

Feeding by both adults and larvae may cause stippling on leaves - spots of discoloration that may turn from yellow to brown to black. Holes may develop in leaves when heavy infestations occur. Plants are not, however, killed by this bug.

Four-lined Plant Bug Damage- Courtesy Purdue University

The four lined plant bug hides under leaves and may be difficult to detect. Look in May and June for signs of stippling on leaves. 


Management Strategies

Least toxic methods of control for ornamentals and edibles would include insecticidal soap, the dormant and summer weight oils and where feasible, removal of egg masses by selective pruning. Authorities say egg-laying sites are easily visible after leaves drop in autumn.

The use of a trap crop is another possible control method to keep the four-lined plant bug away from the crop. Mint is highly attractive to this pest and can be effectively used as a trap crop. The four-lined plant bugs will choose to feed on the mint instead of other nearby plants. Place a barrier, such as a tile, around the mint to prevent the spread of roots. Once the crop is large enough to withstand damage caused by this pest, the mint can be removed.

Whenever using insecticides, be sure the insect you want to control and the plant you are using it on are both listed on the label.


Additional Resources

Four Line Plant Bug - University of Connecticut 

Four Lined Plant Bug Slides - University of Minnesota 

Vegetable MD Online- Cornell University

Greenindustry - University of Wisconsin - Extension