Professor Steven Goldsmith

Purple Mist Flower

The educational landscaping of Austin College’s IDEA Center includes native flowering plants. One of those is purple mist flower (Conoclinium coelestinum). Actually, what you call this plant is somewhat a matter of taste. It goes by several other common names (mist flower, blue mist flower, purple boneset), and some botanists include it in the genus Eupatorium.

Whatever you call it, it is a serious butterfly magnet. I couldn’t get photos of all of the species that were visiting it, but there were painted ladies

Skippers (Hesperiidae)

A kind of moth (maybe Yponomeutidae)

A few Monarchs

And lots of Queens

 

The Monarch larvae feed on milkweeds (Genus Asclepius); these plants produce a variety of toxic secondary compounds. The larvae sequester these toxins, and they show up in the tissues of adult monarchs after metamorphosis. The orange and black color of the monarch adults is a warning to predators that they are toxic.

Green milkweed, Asclepius viridis

The queen butterfly looks a lot like a monarch, and there is some debate about why. Queens also feed on milkweeds, although not exclusively, and there is variation in how “distasteful” queens are relative to monarchs. The current understanding seems to be that queens benefit from looking like monarchs because they (the queens) are not that distasteful, but predators with experience with monarchs will avoid queens too. This is a form of “mimicry.”

Animal Behavior in the field, and predation in action

My Animal Behavior class went out recently to observe foraging behavior of honeybees. There is a lot of goldenrod (Solidago sp) in many places in north Texas at this time of year, and it attracts many species of pollinating insects.

I let the students watch the insect pollinators for a little while, and observe what pollinating insects are present, before asking them what “behavioral assays” we could quantify about honeybee foraging. I led them into what I want them to do by pointing out things like “they move from one flower to another,” which gets the response, “we could count how many flowers they visit” to which I added “per unit time.” I pointed out that they spend a certain amount of time on each flower before moving to another, which got the response “we could measure how long they spend on each flower.”

Then I asked them “what comparison can we make that will allow us to do a statistical analysis” of “flowers per minute” and “seconds per flower.” Fortunately there were a lot of other flowering “DYCs” in the place we were, so they pretty quickly figured out that we could collect the same data set on another plant. So we got “flowers per minute” and “seconds per flower” on goldenrod and bitterweed (Helenium amarum).

The statistical analysis shows significant differences between the plants in these foraging parameters.

I divided the students up into pairs (actually they divided themselves up), with one person being the observer and one being the recorder. I had the foresight to bring digital stopwatches so they could record time spent per flower to the nearest 1/100^th of a second, and they could time 1 minute observation periods during which they counted how many flowers the bees visited. I also brought pre-prepared data sheets that were arranged so that SPF and FPM data could be easily recorded.

Early on during our data collection, one of the pairs of students noticed what they thought was a honeybee behavior strangely. When they looked more closely, they saw that it wasn’t behaving strangely, it wasn’t behaving at all – it was dead, in the grips of a yellow crab spider (AKA goldenrod crab spider, AKA banana crab spider).  The spider is very cryptic.

When I looked more closely, I saw that it wasn’t a honeybee, either – it was a flower fly (family Syrphidae). These are honeybee mimics, and they forage in the same places that honeybees forage. Obviously the crab spider didn’t care whether it was a bee or a fly.