Boxelder, red-shouldered and scentless plant bugs
Click for larger image Despite their preference for golden raintree (Koelreuteria), these red-shouldered bugs (Hemiptera ) often drown in rain storms and proliferate in hot, dry years

As adults, scentless plant bugs, Jadera haematoloma, also known as red-shouldered bugs, are flattened insects about 1/2 inch long and 1/3 inch wide. They are black, bluish-black or brownish-black with red coloring on the eyes, eye orbits, shoulders and borders of the abdomen. The segment behind the eyes has three red lines running lengthwise. Nymphs (immature insects) are mostly reddish with a brown thorax, antennae, beak and legs. The young develop black markings and wing pads as they develop.

Adults and nymphs feed by sucking the sap from seeds, flowers, leaves, and fruits of trees including plum, cherry, apple, peach, grape, chinaberry, western soapberry, ash, maple, and golden raintree. Their primary host is boxelder.

Symptoms and Diagnosis

Scentless plant bugs cause little damage, but young fruit may be scarred or dimpled. In the fall, winged adults and large nymphs seek overwintering shelter. They enter homes through cracks and crevices around foundations, windows and doorframes. In the wild, they also find winter shelter in piles of debris as well as crevices and holes in trees. Adults reappear in the spring and often sun themselves on light-colored walls. When they are in homes, the bugs may stain curtains, paper and other things with their fecal material. Although medically harmless, when the scentless plant bugs appear in large numbers either outdoors or inside, people become alarmed. They may be confused with boxelder bugs, which also may appear indoors in large numbers.

Life Cycle

Adult females over-winter and deposit eggs in crevices and bark cracks in the spring at bud break. Nymphs hatch in about two weeks and go through several stages (instars) on their way to becoming winged adults. There may be two generations or more each year.

Integrated Pest Management Strategies

1. Rake up seeds. Rake up the seeds that the bugs are feeding on if they are a nuisance in lawns or play areas. They are especially prevalent around goldenrain trees. Hand collect bugs where they occur in small concentrations on a plant.

2. Sweep or vacuum. Sweep or vacuum plant bugs if they appear indoors in large numbers. Be sure to empty the bag or clean out the vacuum into a paper or plastic bag that you can then destroy.

3. Remove host trees. Remove goldenrain tree, chinaberry, boxelder, plum, cherry, apple, peach, grape, western soapberry, ash and maple from the immediate area.

Organic Strategies

All of the recommended IPM strategies are strictly organic approaches.

More images:

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It's easy to see why these red-shouldered bugs are sometimes called goldenrain tree bugs when massed on the trunk of golden raintree (Koelreuteria)
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Red-shouldered bugs (Hemiptera ), black with red epaulets, and boxelder bugs, black with orange-edged wings, congregate together on maple (Acer); nymphs with partially formed wings also present
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Adult boxelder bug (Hemiptera ) on maple (Acer); note, black wings with yellow-orange edges; nymph, without fully formed wings, also present
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Red-shouldered bugs, also called golden raintree bugs (Hemiptera), on maple (Acer); adults have black wings with red epaulets, nymph has partially formed wings