Recently, you may have noticed a new orange and black insect on your milkweed. Although it may resemble a boxelder bug, it is actually the large milkweed bug, Oncopeltus fasciatus.
Usually found in groups on the stems, leaves and seed pods, their presence may seem ominous; however, they are harmless to the plant or any other insects, like the Monarch butterfly, that calls the milkweed plant home. Their food of choice is milkweed seed, obtained by piercing the seed pod.
Milkweed bugs undergo incomplete metamorphosis, which means that the nymphs look very similar to the adults, minus full wings and a varied color pattern. Their life cycle includes 5 instars before reaching adulthood. All stages of growth can be found on milkweed plants in late summer. Adult milkweed bugs only have a lifespan of about one month. This short lifespan is one more reason that they are considered more of a nuisance than a threat. They just don’t live long enough to do much damage.
As I mentioned earlier, controlling these little pests isn’t really necessary due to the minimal harm they cause as well as the short time that they are present. Living with the damage may be the best option. However, if the number of milkweed bugs reaches infestation level, they can be controlled with insecticidal soaps. This method is safe and effective. To help prevent an outbreak next year, be sure to remove all leaf litter and spent stalks this fall. Eliminating overwintering sites for milkweed adults will help to decrease next year’s numbers.
It seems to be the general consensus among gardeners that if you have milkweed in your garden, you are going to have milkweed bugs, but that shouldn’t deter you from including these plants in your landscape. With all the wonderful benefits that milkweed has to offer – a safe haven for monarch eggs, a food source for monarch caterpillars – dealing with a few milkweed bugs is a small price to pay.
By Bethany O’Rear, Regional Extension Agent, Alabama Cooperative Extension System. Contact Bethany at firstname.lastname@example.org.
The Alabama Cooperative Extension System (ACES) operates as the primary outreach organization for the land-grant functions of Alabama A&M and Auburn Universities. ACES is committed to affirmative action, equal opportunity and the diversity of its workforce. Educational programs of ACES serve all people regardless of race, color, age, sex, religion, disability, sexual orientation, or national origin.