Late-Autumn Insects

Last week, the coming winter teased us with snow flurries mixed in with the rain. But, during the first week of November, the temperature rebounded to the 70s. The breeze is gentle, the afternoon sun is hot and a few insects are active in some sun-warmed patches of our backyard.

On the garden’s last purple coneflower, a yellow-green, spotted beetle, similar to a ladybug at first glance, nibbles on the coneflower’s center.  It is a spotted cucumber beetle (Diabrotica undecimpunctata).  And, though it’s a garden pest, it won’t survive the Minnesota winter, so I let it stay. It looks beautiful on the deep magenta bloom.

Spotted Cucumber Beetle

Spotted cucumber beetle (Diabrotica undecimpunctata) on a purple coneflower.

Across the yard in another sunny spot, bright red insects huddle together on a common milkweed pod. They include three different developmental stages, or instars, of the same insect, the large milkweed bug, (Oncopeltus fasciatus).  They use a tubelike mouth to inject digestive enzymes into the pod and then suck out the partially digested plant material.  Because they eat milkweed, they have the same toxicity found in monarchs and other insects that dine on the plant.  When I first noticed them a few weeks ago, I thought they were red aphids until I spotted an adult on the pod.  Over time, they began to grow larger, develop black markings, and become darker red.  Like the spotted cucumber beetle mentioned above, the large milkweed bug is migratory and those still here won’t survive our northern winter.

Early instars of Large Milkweed Bug

Early developmental instars of large milkweed bug (Oncopeltus fasciatus).

Large milkweed bug in developmental stages.

Large milkweed bug in several developmental stages on a common milkweed pod.

The orange shells of Asian lady beetles (Harmonia Axyridis) glow where they’ve settled on the sun-warmed brick of our house and on a few hardy garden plants.  Unlike the insects mentioned above, these beetles survive the Minnesota winter.  They were introduced into the southern United States in the mid-1900s to help control agricultural pests and first appeared in Minnesota in the 1990s, according to University of Minnesota records.  To some people they’re pests because the beetles often find a way inside in the autumn. But, they also eat aphids found on trees, in gardens and on agricultural crops.  The easiest way to distinguish Asian lady beetles from native species is by an “M” or “W” mark (depending on the viewing angle) on the thorax between the head and abdomen.  (More about Asian and native ladybird beetles in another post.)

Asian lady beetle on goldenrod.

Asian lady beetle (Harmonia Axyridis) on goldenrod.

Asian lady beetle on 'Henry Kelsey' rose.

Asian lady beetle on ‘Henry Kelsey’ rose.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s