Field report — Speak for the Trees

June 29, 2026

and 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.

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June 26, 2026

and 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 — 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.

Monarchs laying eggs on milkweed

June 26, 2026

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.

July 13, 2026

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.

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Pale Snaketail emerges in urban river under dissolved oxygen stress

July 20, 2026

dragonflies emerged this month along the South Platte River — a finding that carries weight in an urban waterway. These elegant damselflies (Gomphus pallida) require clean, well-oxygenated streams with gravelly bottoms to complete their aquatic nymph stage, which typically spans two to four years buried in sediment. A single adult snaketail is therefore a window not into this season's conditions, but into water quality that held steady years in the past, when that nymph was developing.That context makes the current crisis harder to reconcile. Dissolved oxygen in the creek system has collapsed this month, plummeting to 2.8 milligrams per liter — well into lethal stress for most aquatic invertebrates. Whether the larva that became this adult found a cleaner refuge upstream, or simply experienced milder conditions before the freefall, remains unknown. What is clear is that the broader dragonfly community — , , , and a dozen other species active in the parks and ponds along the Platte — reminds us how much ecological work these urban water bodies still perform. Even as the river itself teeters, they hold.

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Night herons hunt at dusk

May 30, 2026

The air grows still along the wetlands near the American Tobacco Historic District as the sun drops behind the tree line. Light shifts from gold to gray, and the sounds of the day begin to fade. This is when the Yellow-crowned Night Herons emerge from their roosts among the magnolias and green ash, stepping deliberately into the shallow water.A night heron stands motionless at the water's edge, its stocky body balanced on long yellow legs. The bird's head tilts slightly as it watches the bottom through the darkening water. It waits. Minutes pass without movement except for the slow rise and fall of its chest. Then, with sudden precision, the thick black bill strikes downward and emerges with a crayfish clamped between its mandibles. The heron tosses its head back and swallows the crustacean whole.Crayfish move more freely as darkness approaches, leaving their rocky hiding places to forage in the open water. They scuttle backward when threatened, their claws raised in defense, but the night heron's strike is faster than their retreat. The bird's eyes are positioned to judge depth accurately, and its neck muscles can drive the bill through water with enough force to penetrate a crayfish's shell. During nesting season, both parent herons hunt through the evening hours, returning to their stick nests with crops full of crayfish, small fish, and aquatic insects. The young grow quickly on this protein-rich diet, their gray down giving way to the streaked plumage of juveniles.The night heron steps forward into deeper water, each movement deliberate and controlled. Other species share this hunting ground at dusk. Common Grackles wade in the shallows, probing for insects, while Eastern Pondhawks patrol the air above the water's surface. But the night heron occupies its own niche in this timing and technique. As the last light fades, it becomes a shadow among shadows, perfectly adapted to the boundary between day and night. The water laps gently against the muddy bank, carrying the scent of wet earth and new leaves.