“Submarine cottages”

Post by Jen Berlinghof

Late spring and early summer are busy seasons for children visiting the Lake County Forest Preserves for pond study programs. The shorelines of ponds pulse with the excitement of students, nets in hand, ready to discover the macroinvertebrates teeming under the water’s surface. The most delightful find this season by students has to be what Henry David Thoreau once called the “submarine cottages” of caddisfly larvae.

Students patiently fill their buckets with wiggly tadpoles and hulking crayfish. What appears to be an insignificant, teeny stick in a student’s pond bucket suddenly transforms when placed under a microscope. The “stick” suddenly springs to life, as students notice the head of a caddisfly larva unsuspectingly pop out of one end.

Caddisflies are insects in the order Trichoptera, one of the largest orders of aquatic insects. The larvae are widely distributed in various freshwater bodies, and a few species inhabit marine environments. Some consider caddisfly the aquatic cousins of moths. Only terrestrial for a brief period as adults, caddisflies spend most of their lives as larvae and pupae in a wide variety of waterways.

Their success as an order is directly tied to their unique ability to make silk strands, which is used to create portable homes and, in some cases, nets for filtering food. These unique silk retreats have some real advantages when it comes to camouflage, physical protection, food acquisition, and respiratory efficiency.

Caddisfly larvae resemble caterpillars tucked into “sleeping bags” adorned with stones, sand, sticks, and bits of plants. The larvae have silk glands in their lower lips and use this silk to create temporary homes and affix their cases to large rocks or woody debris. By attaching to substrate, they avoid being carried away by the current. The natural materials attached to the outside of the cases not only help weigh them down to prevent drifting, but also serve as amazing camouflage.

Some species create flat, thin extensions on their cases to increase the surface area, which allows them to sprawl on top of soft sediments. Others encase themselves in super long tubes burrowed into the mud, secure inside, never even contacting the muck surrounding them.

While most caddisfly larvae eat algae and plants, some species forgo homebuilding all together and use their silk to catch food instead. These net-spinning species construct mesh silk nets that strain edible particles of plants, crustaceans, and insects from the water.

Caddisflies will spend anywhere from two months to two years in the larval stage before pupating in the water. The case where they spent the larval stage will be modified into a cocoon with the addition of a porous, silk sieve plate to the rear of the case. This allows water in, and with it a fresh supply of dissolved oxygen, while keeping predators out. The cocoon is capped on top with stones or plants and the whole thing is glued in place with silk to a rock or log.

After a few weeks, the caddisfly will cut the pupal case open with its sharp jaw. Many species use the pupal skin like a raft, drifting to the edge of the water to dry their wings before flying to nearby vegetation. Adult caddisflies are mostly nocturnal and live about one month, feeding on nectar with sponge-like mouthparts.

These insects play an important role in the function of freshwater ecosystems. Most species are sensitive to pollution, so the diversity and abundance found in our wetlands can provide useful information about the environmental condition of our waterways.

With the exception of net-spinning caddisflies, each species creates its own, unique abode. Currently, there are 15 documented species of caddisfly in Lake County, Illinois, and likely even more out there—waiting to peek their heads out under the microscope.

Dwindling lights

Post by Jen Berlinghof

At a recent Firefly Campfire at Ryerson Conservation Area, kids and adults alike were flitting around, as fast as the fireflies they were trying to catch. For many of the children, this was their first time experiencing the age-old summer tradition of capturing living light. While the woods that night sparkled like the fourth of July, many of the adults lamented that their yards didn’t have many fireflies—certainly not like the numbers they remembered chasing as children. Turns out they may be on to something.

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Widespread anecdotal evidence of these dwindling evening displays have prompted scientists to take a look at possible reasons. One big culprit to the demise of these bioluminescent beetles seems to be the one thing that makes them so special: light. Continue reading

Des Plaines River Trail—Kilbourne Road to Independence Grove

Post by Jen BerlinghofIMG_7700

Our adventure to traverse the entire length of the Des Plaines River Trail continued with our trek from Kilbourne Road to Independence Grove Forest Preserve under the shining sun and heavy air of late summer. The air was heavy not only with humidity, but with the calls of cicadas, tree crickets, and katydids melding into a three-part harmony that signaled the end of summer. The air was also pregnant with the perfume of flowering plants. It was clear that this hike belonged to the bugs and blooms. Continue reading

Acorn abodes

Post by Jen B

My family went on a bike ride last weekend at Ray Lake Forest Preserve. All afternoon, rain sputtered on and off as the clouds played tag with the sun. After climbing up a steep hill, the sky darkened again and we sought refuge under a canopy of large oak trees. One of my sons yelped,”Ouch! That raindrop hurt!” We quickly realized it wasn’t a raindrop, but a storm of acorns jiggled loose by the wind, plopping down on us. The trail became littered with acorns, and the kids began grabbing them. Upon inspection, the boys noticed tiny round holes in many of the acorns—evidence that these nuts were homes to acorn weevils (Curculio spp).

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Final songs of summer

Post by Jen B

As summer winds down, a telltale hum that signals the changing seasons begins to ramp up in the fields and forests. These trills and chirps are the mating calls of tree crickets (Oecanthinae)—a group of fascinating insects that are often heard but seldom known or seen. Their small size and mint green color helps camouflage them amidst the verdant grasses, shrubs and trees of late summer.

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Ghost of the prairie

Post by Jen B

Many years ago, while hiking through a prairie at dusk, I saw a stalk of delicate white flowers. They seemed to rise and hover above the surrounding plants like a group of little dancing ghosts. This was the first and last time I ever saw an eastern prairie fringed orchid (Platanthera leucophaea). Due to its dwindling numbers and hidden habitats, this rare plant has reached almost mythical status—a holy grail of sorts in the Midwest. We’re thrilled that this endangered native orchid seems to be gaining a foothold in the Lake County Forest Preserves, which are home to some of the largest remaining populations. Just this month, one of our restoration ecologists discovered an orchid in bloom (photo below). It was found at one of the preserves known to provide habitat for this species but is the first documentation of a population at the site.

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Virtual camouflage hike

Leaves throughout the forest glowed gold against a backdrop of graying sky as I left Ryerson Conservation Area yesterday afternoon. This morning—as I entered the same preserve along the same road—the dark, skeletal branches were completely visible, stripped of their vibrant leaves that now lay in muddied piles on the forest floor.

These days of November mark a change from crisp colors to muted tones, which offer the perfect backdrop for animals to hide using camouflage. Lake County Forest Preserve educators often teach the concept of camouflage during environmental programs, where students hike in search of animal hides and mounts that have been hidden along the trail. Teachers and scout leaders, peruse our variety of school and scout programs to find a great fit for your group this year. Following is a virtual version of our camouflage hike. Continue reading