Chicago Lake Plain

Compass plant is blooming at 46 sites citywide since May — lakefront to Southwest Side. Its 15-foot taproot takes a decade to establish; when it flowers, the soil has earned it. Settlers once navigated the Illinois prairie by its north-south leaves.

Blue Dashers and Eastern Pondhawks are patrolling the lagoons on the West Side this week — both tolerant species adapted to marginal water quality. This preference for resilience over choosiness makes ecological sense: all three of the major lagoons here are officially designated as impaired waterways, and none have cleanup plans in place.Streamflow has dropped to just over 12 cubic feet per second, roughly a third of the long-term average of 41 feet per second. Warm, still water holds the least dissolved oxygen of the year, creating conditions that only generalist dragonflies can exploit reliably. The visible presence of these species is less a sign of health than of their extraordinary tolerance for stress.

Monarchs and Red Milkweed Beetles have converged on the lakefront milkweed patches this June — a quiet milestone marking the transformation of this urban edge into essential breeding habitat. Three monarch sightings and four beetle records in recent weeks document what appears to be active reproduction on common milkweed — a coupling that persisted through the Midwest's agricultural intensification but has grown increasingly rare.Over the past three decades, the application of herbicides to corn and soybean crops has stripped milkweed from hundreds of thousands of acres across the region, collapsing the landscape resources that monarchs and their specialist associates once took for granted. The migration corridor now depends on fragmented urban and semi-wild refuges like this one. What was once common is now significant.

The common milkweed plants along the edges of Chicago's green spaces are at their best right now. The leaves are broad and flat, dark green, still soft enough to bend without snapping. This is what a female monarch is looking for when she moves low over a patch of vegetation in early summer, and if you watch one long enough, you can see exactly how she decides.She lands on a leaf and drums it with her front feet. This is not random movement. Her feet carry chemical receptors that detect the milkweed's latex compounds through contact, confirming the plant before she commits. She may check several leaves on the same plant, or leave and try another patch entirely. When she finds what she wants, she curves her abdomen under the leaf and deposits a single egg, pale green and ribbed, smaller than a sesame seed, on the underside. Then she moves on. A single female may lay several hundred eggs over the course of her adult life, but she places them one at a time, spread across as many plants as she can find. This distributes the risk. A caterpillar that strips one plant does not compete with its siblings on the next.The milkweed's role here is not passive. The same latex that the monarch detects through her feet is a sticky, bitter sap that fills channels running through the leaves and stems. Most insects avoid it. A young monarch caterpillar, when it hatches, deals with this by cutting a circle into the leaf surface before eating, draining the latex from that section so it can feed safely. Older caterpillars learn to sever the leaf's midrib at the base, blocking the flow to the whole leaf. The plant is not helpless, but the monarch has worked out how to eat it anyway, and the cardenolides in the latex accumulate in the caterpillar's tissues as it feeds, making the caterpillar itself unpalatable to most birds. The monarch does not merely tolerate the milkweed's chemistry; it borrows it.The red milkweed beetle is doing something similar in these same patches right now. It chews a trench around the midrib before feeding, stopping the latex flow the same way the caterpillar does. Both insects have arrived at the same mechanical solution independently, and both carry the plant's toxins in their bodies. The beetle's red and black coloring advertises this to predators just as the monarch's orange and black does. Neither insect is the other's competitor in any serious sense; milkweed patches in early summer can support both, along with the various bees and wasps that come for the flowers, which are just beginning to open on some plants now, the pink-purple clusters heavy and fragrant above the broad leaves.For the monarchs in this area, the early summer generation is the one that matters most for local reproduction. The butterflies that arrived here in late spring came from overwintering sites in central Mexico, and they have already moved north ahead of the milkweed's emergence. Their offspring, the eggs being laid right now, will be the ones that hatch, feed, pupate, and emerge as adults here in Chicago. Those adults will produce another generation before the season turns. It is the last generation of the summer, not these, that will make the long flight south in autumn. The eggs on these milkweed leaves are the beginning of that chain.Common milkweed grows in disturbed ground, roadsides, vacant lots, and park margins, the kind of habitat that exists in fragments throughout the city. The patches near the Loop are small by rural standards, but monarchs find them. Look for the plants where mown grass gives way to rougher growth, the leaves big and paired, the stem thick. If you find a patch, check the undersides of the leaves. The eggs are easy to miss, but they are there.

The air above Montrose Beach fills with wings. Bank swallows and northern rough-winged swallows cut back and forth through invisible columns of insects, their flight paths mapping what we cannot see. The longest days of the year bring the richest feeding, and these two species work the same airspace with different techniques.Bank swallows hunt in tight flocks, twenty or thirty birds wheeling together through the thickest swarms. They are smaller than their rough-winged cousins, built for quick turns and sudden dives. Their white bellies flash as they bank sharply, following the shifting columns of midges and mayflies that rise from the warming lake. The rough-winged swallows hunt alone or in pairs, taking longer, steadier passes through the air. They are slightly larger, with duller brown backs and no distinct breast band, built for sustained flight through scattered prey.Both species time their nesting to this abundance. The aquatic insects emerging from Lake Michigan now spent the winter as larvae on the lake bottom, growing through the cold months. As water temperatures climb past twenty degrees, they begin their synchronized ascent. Midges rise first, followed by mayflies, then caddisflies. Each species emerges in pulses that last days or weeks, creating layers of opportunity that the swallows exploit. The bank swallows, nesting in colonies carved into the sandy bluffs nearby, feed their young on this protein-rich harvest. The rough-winged swallows, nesting singly in crevices and culverts, do the same. Different nesting strategies, same food source.The swallows take insects of different sizes. Bank swallows specialize in the smallest prey, snatching midges and gnats that cluster in dense clouds. Their bills are narrow and precise. Rough-winged swallows take larger prey, including the mayflies and caddisflies that bank swallows often ignore. This division reduces competition between the species, allowing both to thrive in the same airspace. The insects themselves represent months of lake productivity concentrated into a few weeks of flight. Each midge carried back to a nest cavity contains algae and detritus processed on the lake bottom, energy transferred from water to air to the next generation of swallows.Watch the light catch their wings as they turn. The bank swallows move like a single organism, the flock contracting and expanding as it follows the insect swarms. The rough-winged swallows trace longer arcs, covering more territory with each pass. Both species will feed like this until the last insects of the day settle back toward the water, then return at dawn to do it again. The longest days mean the most hunting time, and these are the days that fuel the breeding season.