Here’s your last reminder of our Platte River Prairies field day this Saturday (July 9). The weather looks great and it should be a fun day. I hope to see some of you out there!

A couple weeks ago, I found myself at a recreational area in Omaha described very accurately on its website as “a 250-acre lake surrounded by 940 acres of trees and grasses”. When Kim signed up for a long trail race there, I’d hoped I’d be able to find some prairie to wander around in while she ran all day. No such luck. Most of the grasses turned out to be smooth brome or reed canarygrass and both the grassland and woodland areas were heavily infested with autumn olive and other invasive shrubs and trees. Undaunted, I found a draw between the race path and the lake where a large patch of common milkweed had embedded itself within a matrix of invasive grasses.

My role for the day was to be available to Kim at the end of every three mile lap so I had some time between laps to explore with my camera. The light was decent for the first couple hours of the day, so I conducted an informal survey of the fauna hanging out in the island of milkweed flowers within a matrix of yuck. I was really curious to see how many insects would be able to find their way to the isolated milkweed patch, especially those species that are milkweed specialists.

Most people associate milkweed with monarch butterflies, but there are lots of invertebrates that take advantage of milkweed nectar and a surprising number that can also feed on the leaves, despite the toxic white latex inside. I did see an adult monarch nectaring in the patch (didn’t get a photo) but didn’t find any monarch caterpillars. There probably were some, I just didn’t happen across any. Lots of other insects were present, though, which was a pleasant surprise.

The nectar produced by milkweed flowers attracted a number of small hungry animals, though not many bees or butterflies. Soldier beetles were, by far, the most abundant of those, crawling around the flowers and picking up pollinia (little gel packs of pollen) on their feet. If you aren’t aware of the fascinating story of milkweed pollination, you can read this older post I wrote on that subject. It’s a story worth knowing. Briefly, milkweed pollen is transferred when insects accidentally slide their leg into flower slits, pull out milkweed pollinia, and then slide the same leg and pollinia into the slit of a different flower to complete the process. It shouldn’t work but it does.

A few honey bees were visiting the flowers, but I didn’t see many native bee species. Honey bees probably do a pretty good job of milkweed pollination because their legs are big enough to pick up and deposit pollen. However, they sometimes have trouble extracting their legs from the flower slits. I found one individual that appeared to have died after getting stuck in that exact way. I’m no fan of honey bees but I didn’t celebrate its death. It was an unfortunate and accidental victim of milkweed’s weird sex game.

Because milkweed flowers draw lots of insects to feed on them, they also host predators that hunt those hungry visitors. I saw a couple crab spiders, but none that were particularly photogenic. I did manage to photograph one of the many small long-legged flies that were hunting even more tiny invertebrates on milkweed leaves. They looked like tiny emeralds with wings.

The remaining insects I photographed were members of the exclusive club that have variously evolved strategies for feeding on a plant that is toxic to most others. Monarch caterpillars are in the club but I didn’t find any on this particular day. I did, however, find lots of red milkweed beetles, as well as some milkweed stem weevils and a few milkweed leaf beetle larvae. It’s fun to think about how those insects ended up on this milkweed ‘island’. I assume of the individuals I saw were born right there, but at some point, their ancestors must have struck out on a cross-country trip that ended up leading them to this isolated patch of food plants.

Before too long, the sun broke out of the diffused clouds that had moderated the temperature for a few hours and had provided decent light. At that point, I retreated to the shade and found other ways to entertain myself while Kim and a bunch of other crackerjack runners completed as many three mile loops as they could during the 12 hour-long race. People have funny ways of entertaining themselves, huh? (…is what those runners thought as they glanced down at the weirdo kneeling with his camera among the milkweed plants near their race track.)