August-September 2020 • Nebraskaland 41
similar orange and black pattern, but without full-sized
wings. Those nymphs grow and molt four times before
becoming adults, a process that takes roughly a month.
Adults can't survive cold winters, so many of them migrate
to the south in the fall. A new batch of milkweed bugs then
migrates back to Nebraska the following summer.
After hatching, nymphs of large milkweed bugs tend to
hang out in gangs on milkweed pods. If the pods are open,
they will feed directly from the seeds. However, when the
pods are closed, they may or may not be able to poke through
the pod and into the seeds within. As they grow larger and
more mature, their rostrum lengthens and they're better able
to reach seeds inside closed pods.
During a period when efforts are aimed at increasing
population sizes of milkweeds, especially for monarch
butterfly conservation, it may seem odd to celebrate an
insect that helps destroy its seeds. However, it's not the large
milkweed bug's fault that milkweed numbers have declined.
Milkweed and the various insects that rely upon it for food
have coexisted for many thousands of years. Many of those
insects have used the toxicity of milkweed latex as a defense
mechanism, and they enjoy the benefits of their ability to eat
a plant most other insects eschew, not chew.
Plus, how can you not celebrate the large milkweed bug? It
injects its spit into seeds to predigest them, uses poison as a
weapon and migrates long distances — especially for such a
small insect. The next time you see a mass of orange bugs on
a milkweed pod, don't dismiss them as boxelder bugs (which
have their own fascinating story, by the way). Instead, pause
a moment and admire the bug's bold coloration and watch it
suck the predigested juice out of a milkweed seed. Or, just
admire its color.
N
Chris Helzer is the Nature Conservancy's director of science
in Nebraska.
From left to right, large milkweed bug, small milkweed bug and boxelder bug. Note the solid black band across the back of the
large milkweed bug, the orange X on the small milkweed bug and the much smaller amount of orange on the boxelder bug.
An adult milkweed
bug has its rostrum
(mouthpart) inserted
into a milkweed pod
so it can feed from
the seeds inside.
