Blandy Experimental Farm & Presquile National Wildlife Refuge – Blog Post 3

We returned to Blandy Experimental Farm last week and spent three days doing pollinator watches. During each pollinator watch, which typically lasted between ten and twenty-five minutes, we recorded the species and visit duration of insects on an umbel of a common milkweed plant. An umbel is a cluster of flowers on a milkweed stem that emerge from a common point. Before starting each pollinator watch, we recorded some measurements for each plant, such as height and number of leaves, as well as recorded the number of pollinia that had been either inserted or removed from the umbel. Each umbel typically had between thirty and sixty flowers, and each flower contained five pollinia before any insertions or removals by insects. We used optivisors to carefully count insertions and removals after insects left the umbel. We also set up some video observations for twenty minutes per umbel. For these observations, we recorded the number of pollinia insertions and removals at the beginning and end of each video. We photographed images of the leaves of the videoed plants so that we will be able to use ImageJ to do some herbivory calculations later.

After leaving Blandy, we went to Presquile National Wildlife Refuge, where we examined two milkweed transects – one containing over ninety common milkweed plants. We took common milkweed plant measurements, mapped plant locations, and measured plant leaf absorbance readings using the spectroradiometer. The temperature reached over 39 degrees Celsius during our field research day at Presquile, so we thankfully finished all of our data collection in one day and then headed back to Williamsburg in the evening.


An insect visitor (Atteva aurea) on a milkweed umbel


  1. mfguzzano says:

    This is a cool thing to research! Do you think your presence and the presence of other researchers had any impact on the type and number of visitors to the plant? How can you tell a pollinia had been inserted by an insect as opposed to one naturally occurring on the plant? How active are these pollinator watches, are you constantly seeing bugs or is it only every once in a while that pollinators show up?

  2. mrdonnan says:

    We observed similar numbers of insect visitors in both the video and the in-person observations, so I do not think our presence impacted them. The pollinia inserted by insects are sticking out of the stigmatic slits on each flower whereas the pollinia naturally occurring on the plant are contained within each stigmatic slit. The activity in the pollinator watches depends on a lot of factors, such as weather and time of day. Sometimes we observe a lot of insect visitors, but sometimes we observe only a few or none.

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