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Some plants and pollinators have unique relationships. Take the rush milkweed.

Most years our rush milkweed plants only produce one or two seed pods each.

This year, however, the plants are covered with seed pods.

Why?

To figure out, we need to go back a few weeks. At that time the plants were covered with flowers.

We also saw a lot of tarantula hawk wasps visiting the flowers.

Although they are clumsy giants, tarantula hawks are especially good at pollinating milkweeds.  Their long legs slide into the grooves in the flowers, where they collect the sticky sacs of pollen called pollinia (for more information, see BugGuide). When the wasps visit the next flower, the process is reversed, leaving the pollinia behind to pollinate the plant.

This year the tarantula hawk wasps were abundant and now the seed pods are, too, which hopefully means

soon we'll see more milkweed seeds,

which will glide away on their silky parachutes to make more rush milkweed plants, which are

good for the monarch caterpillars that eat them, and

which turn into monarch butterflies, important pollinators for many other wildflowers.

All thanks to tarantula hawks!

The rush milkweeds are lovely this week.

They are flowering.

Here is what the plants looked like on March 19, a month ago.

The stems were covered with oleander aphids.

On April 17, 2018 you can't find a single aphid.

What did I do to get such clean plants?

Nothing. Let nature take its course.

Insects like aphids have boom and bust cycles.

Back on March 19, these aphids were under attack. They were turning into mummies, which means they were parasitized by tiny wasps.

The aphids were also being eaten by flower fly larvae, aphid flies, and a few other insects.

Inside, the plant might have been mounting a defense, too. Plants can increase their chemical fortifications in response to insects feeding on them. Milkweeds are well defended because they contain cardenolide toxins, as well as a milky latex. The aphids can overcome the plants toxins better than most insects, but eventually it is probably has a toll and the aphids are weakened.

Although they are gone right now, the oleander aphids are likely to be back again. It is a natural cycle.

Did you guess the identities of the milkweed insects from last week?  Let's check.

  1. The yellow-orange insects on the stem are aphids. More specifically, they are the oleander aphid, Aphis nerii.  Hint:  Aphids are the ones with two "tailpipes" or cornicles on the back.

2. The red and black one insect might be hard to tell from this angle, but it is a true bug. A little one with two white dots in the wing is a small milkweed bug, Lygaeus kalmii.

3. This one was tough because the photograph isn't very close. It is an assassin bug, Zelus renardii. It is probably waiting for a bee or fly to capture.


4. I think everyone recognized the praying mantis. In this case, it is the Mediterranean mantis,  Iris oratoria. (See previous post).


5. This one is tricky. Cirrelda correctly recognized it is a lady beetle.


6.  The pale green oval at the end of the hairlike stalk is the egg of a lacewing. (Life cycle in previous post).


7. The cute striped caterpillar will turn into a monarch butterfly.

At this time of year, the butterfly will probably migrate farther north to lay its eggs on another milkweed plant.

We're glad it stopped by.