What’s that bug?

Written by Mary Free, Certified Master Gardener

Oncopeltus fasciatus (Milkweed bug) on Lonicera fragrantissima (Winter honeysuckle) © Mary Free

If you think that this red-orange and black insect is a large milkweed bug (Oncopeltus fasciatus), then you would be correct. But surely those are not milkweed flowers. No, milkweed plants die back in the fall. These half-inch long blossoms belong to Lonicera fragrantissima (winter honeysuckle), a semi-evergreen shrub that blooms in winter.

You may know that large milkweed bug females lay eggs on milkweed plants spring into fall. The eggs hatch into nymphs or “instars” that are immature, wingless versions of the adults. It takes about a month (or more depending on the temperature) for them to undergo five growth stages, gradually developing wings. After each stage, they molt. After the 5th instar and fifth molt, they become a winged adult. This life cycle, called incomplete metamorphosis, usually is spent entirely on milkweed plants, like native Asclepias tuberosa (butterfly weed).

Oncopeltus fasciatus (Milkweed bug) On Asclepias tuberosa (Milkweed) © Mary Free

You can see two mid-instars and two late-instars along with an adult large milkweed bug looking for food on an open milkweed seedpod.

The bugs suck juice from the milkweed seeds and from the plant tissue. Although all parts of the milkweed plant are poisonous (except for the pollen and nectar), milkweed bugs are able to absorb the toxin in their bodies. Their aposematic coloration warns predators to stay away because they have become poisonous too. Since they are relatively easy to breed, large milkweed bugs often are used for elementary/middle school projects and scientific research. When raised in captivity, if the bugs eat raw, cracked sunflower seeds instead of milkweed, then they do not become toxic.

Usually adult large milkweed bugs live only about one month. So what was that adult bug doing on winter honeysuckle in early February?  If adult milkweed bugs have not reproduced before winter, then they hibernate and wait until spring to mate and lay their eggs when the milkweed plants are growing again. On a temperate winter day, they may roam about. Adult milkweed bugs sometimes drink nectar and suck juices from plants other than milkweed. Apparently this bug found Lonicera a suitable substitute for milkweed in winter. Who knew? Did you?

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