Milkweed bugs
Click for larger image Milkweed bug adults (Hemiptera) mating on the seed pod of a honeyvine milkweed (Asclepias)

The large milkweed bug, Oncopeltus fasciatus, is colored orange-red and black. It has a long proboscis and is a piercing sucking insect. It feeds on the seeds, leaves and stems of milkweed (Asclepias). It is found in small groups on milkweed often on the stems, leaves and on the seed pods. The bodies of milkweed bugs contain toxic compounds derived from the sap which they suck from milkweed. Milkweed bugs are true bugs (Hemiptera) . They are used as research insects because they are easy to use in the laboratory, have a short life cycle and are easy to manipulate.

Symptoms and Diagnosis

Milkweed bugs are more of a nuisance than a threat to milkweed plants. They feed on the seeds by piercing the seed pod and can be found in all stages of growth on the plants in mid to late summer.

Life Cycle

The milkweed bug undergoes incomplete metamorphosis. The nymphs look like adults but do not have full wings and their color pattern is different. They have five instars before they reach adulthood. Black wing pads appear early in their development. Eggs are a light lemon yellow changing to a reddish color. Incubation period is about four to five days. Each molt lasts five to six days. An adult will live for about one month. The insect overwinters as an adult.

Integrated Pest Management Strategies

1. Live with the damage. Milkweed bugs do little damage and are only present for a short period of time. Just living with the insects may be the most prudent thing to do.

2. Sanitation. Remove leaf litter and spent stalks in the fall to eliminate overwintering sites.

3. Use insecticidal soap. For quick control of an infestation insecticidal soaps are very effective and safe. Good coverage of the insects with the spray is necessary for it to be effective.

4. Use chemical insecticides. If necessary, use chemical insecticides as a last resort. Use caution when selecting insecticides as some may be harmful to beneficial insects.

Organic Strategies

Strategies 1 and 2 are strictly organic approaches. For an organic approach to Strategy 3, consult the Organic Materials Review Institute (OMRI™) for appropriate insecticidal soap products.

More images:

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On honeyvine milkweed (Asclepias, milkweed bugs (Hemiptera) could be considered beneficial for feeding on the seed pods thereby reducing the seed production of this weed.
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Milkweed bugs nymphs (Hemiptera) on the seed pod of a honeyvine milkweed (Asclepias)
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Adult milkweed bugs (Hemiptera)on milkweed (Asclepias)
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Adult milkweed bug (Hemiptera) on milkweed (Asclepias)
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Milkweed bug nymphs (Hemiptera) in various stages
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Milkweed bug nymphs (Hemiptera) in various stages