August 11 - 20
Racine has 13 hours and 42 minutes of daylight and Superior has 13 hours and 57 minutes of daylight at the end of the period. Southern Wisconsin loses 26 minutes of daylight and northern Wisconsin has 30 minutes less than the previous period.
Freshwater Mussels: Large river systems are home to a tremendous number of aquatic species. A little-known but highly important part of large river systems are the freshwater mussels.
Freshwater mussels are bivalves consisting of two shells surrounding the animal’s soft parts. The shells have various shapes, colors, textures and protuberances including wings, knobs, and ridges. The two shells are held together by a hinge. The inside of the shell consist of a pearly colored material. Most freshwater mussels have a fairly large triangular shape tooth. The size and shape of the teeth vary among species.
Shell growth starts at the beak and grows outward from there. Freshwater mussels lay down growth rings much like annual growth rings on trees. In some species, the shell shape is different between the sexes.
The lifecycle of freshwater mussels is straightforward but complex. The male releases sperm into the water. The female draws it in through her siphon. The eggs are fertilized in the female. The resulting larvae, called glochidia, resemble miniature mussels (or for those older gamers - miniature pacmans). These glochidia are emitted through an exit siphon. To survive, they must attach to a vertebrate host, usually of fish. However, salamanders are sometimes hosts.
The glochidia attach to the fish’s gills and remain as implanted parasite for a few weeks or months. During this time, the young mussels grow and develop organs. After a few months, the juveniles drop off in fall onto the streambed. If the substrate and currents are favorable, the young mussels survive and begin their 1 to 8 year maturation. Adults of some species have been known to live over 100 years.
Muscles are important in Wisconsin’s river systems for various reasons. The shells provide important spawning and hiding habitat for various fish and insects. As filter feeders, mussels are primary consumers of plankton and are important in the food web of large rivers. They convert and accumulate nutrients from plankton. Since they are quite sensitive to changes in habitat and water quality, they are good indicators of changing environmental conditions.
Wisconsin has an abundance of mussel species. They are found in virtually every large river. Naturalists should take an opportunity during late summer and early fall to look for freshwater mussels. This time of the low water, freshwater mussels are most easily found. Simply search sandy, rocky and gravelly areas for shells.
They sometimes are stranded in low-water pools and conservation minded outdoor enthusiast can help freshwater mussels by placing them back into deeper waters. A sampling of freshwater muscle species that may be encountered in the larger rivers of the state include:
The washboard – the shell is black brown heavy and very large. This species should be looked for in the Wisconsin, Mississippi and St. Croix rivers. The host fish include bluegill, yellow perch and freshwater drum.
Pistol grip – this threatened species has a brown and black shell that is moderately heavy and elongated. The host fish are catfish and bull heads.
Winged Mapleleaf – the shell is brownish with wide broken green rays. Tubercles arranged in two rows radiate down from the beak onto each valve. This species is endangered and is found only in the St. Croix River.
Mapleleaf – this species is highly variable and shell colors from brownish to greenish or yellow. A V-shaped pattern of tubercles begins at the shell beak and radiates down on each valve. This common species has several host fish including catfish and bull heads.
Monkeyface – the shell is brown to horn-colored, usually with zigzag green lines. Large tubercles on the ridge are present. Known host fish are sunfish and bass.
Wartyback -the shell is brown or yellow outlined on the foot and an angular end. There are there are a few tubercles that extend onto each valve. Host fish include crappie and catfish. This species is threatened in Wisconsin.
Pimpleback – the shell is brown or yellow with one or more broad, green rays on each beak. The adult shell has a few rounded tubercles in no predictable pattern. Host fish are bull heads and catfish. This species appears to have healthy populations in Wisconsin.
Threeridge – the adult shell is brown or black and moderately heavy. The shell is sculptured and includes several concentric rings. The adult shell typically has three wide ridges. There are at least 10 fish species that are host and the species appears to be healthy in the state.
Wabash pigtoe - the shell is red, yellow or brown with occasional rays. The ventral margin is concave. The hosts are silver shiners and creek chubs and the species appears to be healthy in the state.
Purple Wartyback – the shell is brown or black and very heavy. The interior shell surface is deep purple in recently dead specimens. Numerous tubercles appear on the shell. This species prefers rocky areas, riffles and fast water with recent records from the Chippewa and St. Croix rivers. This threatened species has many hose fish including bullhead and catfish.
Round Pigtoe – the shell is heavy brown or black. It has a convex ventral margin. Host fish are shiners minnows, and dace. The species is relatively still easy to find in the St. Croix and Wisconsin rivers.
Spike – the shell is moderately heavy brown or dark green. It is inflated and elongate with the posterior and pointed. This species inhabits sloughs and main channel borders. It is relatively easy to find.
Pond Papershell – this common species has a green or yellow fragile shell with green rays. No teeth are present. There are at least 19 species of fish that are known to be host for this species.
Flat Floater – the shell is large and flat being very compressed, light brown often with green rays. Several fish species are hosts including: shiners, catfish, and sunfish. Populations appear to be healthy and large river systems.
Giant floater – the shell is yellow green or brown often with green rays. It is very thin and inflated at one end. This species is found in impounded waters on large rivers and has many host fish that include sunfish and largemouth bass.
Elktoe – the shell is elongated and nearly rectangular with inflated yellow or green background interrupted with green raise. It inhabits small to large streams and does not have a known host.
Slippershell – the shell is inflated, boxlike, with yellow green or brown colors, sometimes with green rays. This species inhabits small to medium-size streams and has a host fish called the banded sculpin.
Rock Pocketbook – this Wisconsin threatened species has a brown or black large shell. The shells are very inflated and quite heavy. Prominent beaks are sculptured into due to divergent rows of tubercles extending into each valve. Known host fish are channel catfish and rock bass.
Salamander Mussel – the shell is elongated and somewhat inflated with yellow or brown colors. The shell is about 1 ½ inches long smooth and cylindrical. This mussel lives in small colonies beneath rocks. The host species is mud puppy. This species is considered threatened in Wisconsin.
White Heelsplitter – it has a very compressed brown or black shell. Often with several large ridges that extend into the shell. This species is widespread, but not common and has several host species of fish including common carp, green sunfish and largemouth bass.
Fluted Shell – the shell is yellow or green with green rays. It is very elongated almost rectangular and quite compressed. It inhabits small streams to large rivers. The fish hosts are yellow perch, walleye, northern pike, hog sucker, and largemouth bass.
Threehorn Wartyback – the shell of the species is yellow, green or brown. Each valve has a role of three large rounded tubercles or horns. Host species are all fish and include minnows, shiners, and days. The populations appear healthy and Wisconsin.
Mucket – the shell is heavy almost oval with yellow or brown background and green rays. Several species of fish are hosts including bass and crappies. This formerly common species is becoming rather rare.
Butterfly – the shell is yellow or brown with interrupted green rays comprised of V-shaped marks. The species is endangered in Wisconsin being confined to the very largest rivers. The only known host fish is freshwater drum.
Hickory Nut – the shell is moderate to very heavy with yellow or brown background colors and green or brown rays. This species is of great concern because its host fish, the shovel nose sturgeon is rapidly declining in the state.
Deer Toe – the shell was nearly triangular and a variable in color with interrupted rays of green or brown consisting of V-shaped marks. This species appears to be healthy in Wisconsin waters and its host fish is unknown.
Fawnsfoot -the shell is very similar to deer toe. It is quite triangular with variable colors, but the V-shaped marks are not as obvious. This uncommon species has the freshwater drum as its host.
Fragile Papershell – the shell is yellow or green with green rays. It is slightly inflated with reduced teeth. This species is tolerant of water manipulation and inhabits several impounded areas. The host fish is freshwater drum and the populations are healthy.
Pink Papershell – the shell is pink, yellow, green or gray. Concentric bands of several colors are common and the shell is usually smooth and shiny. This species also has the freshwater drum as its host. Populations appear healthy in the state.
Pink Heelsplitter – the shell is large and compressed with brown background colors. Presently the species is widespread, but appears to be declining. Its host is unknown at this time.
Lilliput – this species is very small, less than 1 inch long, with brown or green oval shell. Currently this species is widespread and abundant. It prefers soft substrate of backwaters and its host fishes are green sunfish, bluegill, and crappie.
Black Sandshell – the shell is large, elongated, inflated and usually dark brown or black. It is declining in the state. Several fish species act as hosts.
Ellipse – The shell is oval with yellow or brown back on colors and green raise. It inhabits smaller streams and has as many as 15 species of fish as host, including darters and sculpins.
Yellow Sandshell – it has an elongated and inflated yellow shell. Greenish rays are never present. This endangered species prefers clean swept sandy areas in the main channel of large rivers. Its host species of fish are both gar species.
Slough Sandshell – this endangered species is similar to the yellow sand shell except that it has green rays and is more inflated and cigar shaped. This species is often found in wild celery beds and has a host species known as the short-nose gar.
Fat Mucket – the shell is yellow or brown with green rays. It is moderately elongated and very inflated. The populations appear healthy with 14 species of fish known as hosts. Its preferred habitat is shallow water with much aquatic vegetation.
Plain Pocketbook – the shell is yellow, brown, green, red or pink with the colors often forming concentric bands. The shell is inflated with prominent beaks. This species occurs in a variety of habitat types with several fish species as host and his populations appear healthy.
Shorebird migrants: Shorebirds reach their peak in total numbers with adults decreasing, but still in good numbers and the young of the year arriving. Naturalists should look for good numbers of many species. Mid-August is peak time for Baird’s Sandpiper, which nest farther north than any other species with high arctic nesting commencing in July.
Perseid meteor shower: For the average outdoor enthusiast, the Pereid meteor shower is the best one to observe. Mostly it’s the time of year. Lying on the ground looking skyward on a warm August night seeing upwards of 100 meteors per hour flash across the sky, what a memorable experience?
In 2015, the Pereids will peak on August 12 – 13. These meteors are made of tiny space debris left by the comet Swift-Tuttle. They are so named, because they radiate from the constellation Perseus, This year will be great for viewing, due to the darkness of the sky at new moon. The beast observation time is after midnight.
Mid-August floral peaks: Peak blooming is most predominant in open wet areas, such as prairies, sedge meadows, and fens. Although, forest areas are showing well with goldenrods and aster coloring the forest floor both north and south. Mid-August blooming plant and fruiting observation is best accomplished by visiting these habitats. Several earlier blooming species are setting fruits in August.
Table 1. Native Wildflowers with peak blooming times August 11 - 20
Changing bird migration patterns: Common nighthawks usually reach their peak southward movement in mid-August. This movement may be delayed in some years to later in the month of droughty conditions predominate. The fall migration has many more individuals than the spring migration, due to fact that many lighter colored Great Plains birds loop eastward in their fall migration.
Chimney swifts appear to vanish overnight from breeding chimneys (both natural and man-made). They do not leave the state; they congregated in sometimes huge communal roost and forage in wide circles from these roosts. Many swifts will remain in the state through September, but most people do not get to see them after mid-August. These roosts can have as many as 10,000 birds.
Grassland spiders: August is the perfect time to look for large spiders that inhabit our grasslands and sedge meadows. The easiest to find are the ariopes. They have large web that glisten in the morning dew. Argiopes build huge webs that may be more than 3-feet in diameter. They hang inverted in the center of the web waiting for insects to fly into it. Several species occur in the state – garden yellow, banded, black and yellow and silver – are common species.
Another group of spiders for the naturalist to observe is the crab spiders. This family is well known, because they sit on flower waiting for pollinators or other nectaring insects to come along. The crab spiders, then attach this insects, which are many times much larger. They quickly immobilize the larger insects and feed on them. The goldenrod crab spider can change its color to match the flower color. Look for one or more crab spider species on flowers in fields from now until the first frost.
The Orchard Orioles so active, vocal and colorful in May and June, quietly leave the state.
Roadside wires are still full of swallows, which flock up and migrate in mass. Barn Swallows reach their peak numbers in mid-August.
The Luna moth and Isabella tiger moth (wooly bear caterpillar) have their second broods.
In barrens areas, look for bird drooping moths near ragweed patches or scarlet-winged lichen moth near parches of lichens.
Northwoods naturalists visiting aspen forest at night should be aware that the sleepy underwing moth reaches its peak abundance in mid-August.
Several mushroom species are increasing in numbers that usually lasts well into early October. Boletes, parasol mushroom, Pig’s-ears, anise funnel-cap, and meadow mushrooms should begin making their appearance.
While foraging on succulent blackberries, be aware you may be enjoying the plant with the colorful candy-striped leafhopper. This red and green striped bug is our most recognizable leafhopper.
The clymene haploa hangs around Joe pye weed.
While observing flowers on our wonderful prairies, closely look at the plants for bugs either pollinating or feeding on the plants leaves or juices. Several species of plant bugs are most active at this time of year with many being host specific.
In addition to plant bugs, the observant naturalist should be able to find ambush bugs on flower heads. Two species of medium sized bugs, the American and Pennsylvania ambush bug, are usually found on the flower heads of goldenrod or joe-pye weed. They lie in wait, like crab spiders and pounce on prey holding them fast with strong legs. Both species have black and orange patterns on their backs.
Many times in mid-August adult white-spotted pine sawyer beetles can be seen. They are hard-bodied beetles with spotted backs and very long antennae (horns). They feed on dead conifers in their larval stage. Several species of these long-beetles can be found throughout the summer. Almost of all of the species feed only on one type of tree.
Bluebead lily (berries)
Hazelnut (peak nut volume)
Round-headed bush clover
Smartweed (several species)
American wild mint
Woodland joe-pye weed
Ground nut (pods)
White oak (acorns)
Sedge meadows & moist grassy areas
Sedge meadows & moist grassy areas
Dry to mesic northern woodlands
Conifer forests and swamps
Barrens, dry forest
Dry conifer forests
Dry to moist open areas
Wet-mesic prairies and fens
Dry prairies and fields
Moist open areas and wetlands
Wet prairies and ditches
Moist open areas and wetlands
Native and planted prairies
Dry woods and savannas
Dry woods and savannas
Dry to moist prairies
Sandy prairies and fields
Savannas & dry woods
Bogs and northern sedge meadows
Great Lakes shorelines
Woods and clearings
Floodplains & wet meadows