Monday, July 30, 2012

Milkweed Beetles

Day 176
The Daily DuBrule

Saturday I was doing a garden walk with an enthusiastic group of participants. Someone asked about a white flower in bloom.
That's Asclepias incarnata 'Ice Ballet', otherwise known as the white flowering form of our native butterfly weed or swamp milkweed. See the pods? They look like little milkweed pods. This is one of the many larval food plants for the monarch butterfly. There's a pink version too, right over there...
Both of these plants were self sown from an original plant in a nearby garden. Oh look closely, there are milkweed beetles on them! 

As scary as they look, they don't harm anything. They bore into the stem of milkweed (and it's relatives), overwinter, and then hatch the following year. The sap of the milkweed makes them taste nasty to other predators. This is also true of the monarch larvae. What a cool survival mechanism!
How do I know this? Back in October of 2009 I first spotted these bugs. You really couldn't miss them as there was a cobalt blue stainless steel gazing ball in the garden and they were crawling all over it! A few other visitors to the Natureworks gardens also found them fascinating. I found my friend Michael photographing them, just as I was doing. I assumed that they were beneficial insects eating the gazillions of aphids on the stems of the Asclepias. I was SO wrong.

The aphids were not the target of this bug, the milkweed was! So this time, when I saw them (many months earlier I might add) I knew right away what I was looking at. That's the beauty of an organic ecosystem. Instead of wanting to kill every bug you find you get to look it up and learn about it. Oh, by the way, the ladybug in the bottom right corner of this picture was doing the aphid eating. You go girl!


  1. Ick! I'll have to go check my 'Ice Ballet's... nasty bug!

  2. Actually, it's harmless, just an interesting phenomenon of nature. It has never stopped my Asclepias plants from thriving or spreading!

  3. I am curious if it is completely harmless actually. I had 'Ice Ballet' years ago and each year the stems would get holes all over them and look really awful (this was before I turned into a curious bug lady) so I eventually just ripped the whole plant out. This year I bought another and will watch it closely. Maybe now since my yard is pretty well balanced it will be fine. I do see these bugs around on other plants occasionally.

  4. Huh... was assuming that if it were boring into the stems, that the plants wouldn't like that much. Good to know they're probably harmless. (I'm not seeing any on mine anyway, so I won't worry too much.)