Red Milkweed Beetle: A Total Milkweed Life Cycle

When the Common Milkweed begins to bloom — which is usually near the end of June in Detroit’s Eliza Howell Park — it is the time to start seeing Red Milkweed Beetles. Their whole life revolves around Milkweed plants.

There are many Common Milkweed plants in the park, often in patches, and it is easy to spot Red Milkweed Beetles on a walk through any of the patches this week.They feed on all parts of the plant — leaves, buds, stems.

Red Milkweed Beetles are in the longhorned beetles family, named for the length of the antennae. The antennae are right by the eyes, giving the head a very interesting appearance.

The adult beetles have recently emerged from the soil and will spend much of the summer eating. They do not congregate in large numbers on any one plant (flying from one milkweed to another) with the result that they do little damage to the plant.

In eating milkweed, they accumulate alkaloid toxins in their bodies, just as Monarch butterflies and some other milkweed insects do, making them nearly immune to predators. And, like the other insects that have this milkweed advantage, they advertise their toxicity by their red/orange color.

They don’t need to hide or use camouflage for protection.

This is the season for eating, and it is also the season for mating. Females lay their eggs on milkweed stems by the ground. When hatched, the larvae bore into the stems or dig into the ground and work their way to the roots, where they spend the winter. The adults die in the fall.

It appears this female is not interrupting her eating while mating.

Red Milkweed Beetles are completely dependent upon milkweed plants. Put differently, they specialize in milkweeds. They are common where milkweeds are common and not anywhere else.

I find it fascinating to observe and learn about the life cycles of different insects. This week Red Milkweed Beetle has been the focus of much of my attention.

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