Small Milkweed Bug: New Observation, More Questions

On three different sunny days in mid-March, I found Small Milkweed Bugs on the ground in the wildflower field. It was the first time I have seen these striking orange and black insects this early in the spring.

Small Milkweed Bugs, like Monarch butterflies, feed on milkweeds as they develop. They are resistant to the mulkweed’s toxic compounds (cardiac glycosides) and able to take them into their own bodies, becoming toxic to potential predators themselves. And, like Monarchs, they announce this toxicity by their bright colors.

They overwinter as adults here, emerging from their winter shelters as soon as the weather warms. Monarchs also spend the winter as adults, but they migrate to warmer climates snd are not seen here again until May.

There were several milkweed bugs close together this week, suggesting that they winter together.

There is also a Large Milkweed Bug, very similar in apearsnce and behavior and more common than the Small MB in the park. Large Milkweed Bugs also overwinter in the adult form but might migrate some distance south. I am not sure, but I have never seen them here this early.

A Large Milkweed Bug is on the left; A Small Milkweed Bug is on the right.

Milkweed bugs lay their eggs on milkweed plants and the nymphs (which look somewhat like adults, but do not have wings) feed and grow there. They are often found in clusters.

I think the nymphs in this photo are Latge Milkweed Bugs. Perhaps this year I will learn the difference between the two species in nymph stage.

Milkweed bugs are seed bugs, extracting nutrients from seeds. This photo was taken last November, at the very end of the season.

I was surprised this week to spot a mating pair aming the early bugs. They reportedly lay their eggs on milkweed plants within a few days of mating, but this year’s milkweed plants have not emerged yet. The mating seems premature, but perhaps there is more for us to learn.

I thank these early Small Milkweed Bugs for the opportunity to observe more about their life cycle — and to start my 2021 insect photos. And I thank them for the reminder that there is more that can be learned on future Eliza Howell nature walks.

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