What can we do about those orange and black critters that eat seed pods, damage leaves, and even occasionally eat a young caterpillar? A few won’t do much damage but they like to multiply and we find that if we leave a few, we often end up with more than enough to do damage to our plants.
The photos on this page are of the large milkweed bug, Oncopeltus fasciatus. They are found throughout North America, Canada, the Caribbean, Mexico, and Central America. The small (or lesser) milkweed bug, Lygaeus kalmii, is found in most states as well as Canada.
Although it doesn’t happen often, they will sometimes eat young caterpillars.
Milkweed bugs migrate to areas where temperatures do not drop below freezing in the southern states as well as to Mexico in the fall. In the spring, they migrate north again.
Eggs resemble lady bug eggs and are also yellow when they are freshly laid. As the nymph forms inside the egg, the egg darkens. Nymphs hatch about five days, depending on temperature.
The leaf curl in this photo is classic for the area where the young nymphs hatch and are located on a plant.
Nymphs molt four times, creating five nymph instars, before the final molt which results in winged adults. Their approximate life span is six weeks as nymphs and as adults for six weeks, again depending on temperature.
Many people simply ignore milkweed bugs, allowing them to do what damage they can. Others want every one removed from their gardens.
Any pesticides/insecticides that kill milkweed bugs will also kill Monarch and Queen caterpillars. They can be removed by hand-picking.
When picking by hand, some people wear gloves. They create a horrible stink, like a stink bug.
You can control their population easily. It’s a simple three step method.
1. Prepare a cup of soapy water or half-alcohol and half-water mixture.
2. Pick bugs and nymphs from plants and drop into the liquid.
3. Repeat daily for the first week, every other day the second week, and from the third week on, repeat weekly.
Be aware that the milkweed assassin bug resembles milkweed bugs so much that most people do not notice the difference. Milkweed assassin bugs can be found on any type of plant. They eat small insects, including butterfly caterpillars. Sometimes when they are touched, they stick their rostrum (mouth part) into your skin, resulting in pain that may last for a few days.
Milkweed bugs do not have a ‘neck’ while milkweed assassin bugs have a ‘neck’ and elongated head. Once you see the difference, it is easy to tell the difference between the two insects.