Designated on June 12, 2017, Lawrence Creek SNA is one of the newest Scientific and Natural Areas in the Minnesota DNR’s inventory. It consists of 71.8 forested acres of steep bluffs and deep ravines near Franconia in Chisago County. Included within its boundary is a trout stream, a hunting shack, and an 11-acre state wildlife sanctuary. The sanctuary is closed to the public and visitors are asked to “Stay back from cliffs and off steep slopes” to protect sensitive plant communities. There are no maintained trails, but there is a forest road and worn footpaths that together complete a 3.2-mile circuit of the site.
Visitors to Lawrence Creek SNA this week (May 6 to 12, 2018) will see Pennsylvania sedge in flower and sharp-lobed hepatica and yellow marsh marigold peaking. Other spring wildflowers in bloom this week include bloodroot, white trout lily, large-flowered bellwort, large-flowered trillium, and Virginia spring beauty. Louisiana Waterthrush, a species of special concern, has been heard here. The site contains habitat that may host Cerulean Warbler, Acadian flycatcher, and Red-shouldered Hawk. Three Helmeted Guineafowl were seen in the parking area by a surprised visitor. They apparently belong to the farm across the road and are free to roam the adjacent fields.
Checkered white (Pontia protodice) is a medium-sized butterfly with a wingspan of 1½″ to 2½″. It is a southerly species and is uncommon in Minnesota. There are two overlapping broods here, early June to August (spring form) and July to mid-October (summer form). The wings are white with dark markings, including a checkered pattern on the outer margin. The female has more extensive markings than the male, and the spring form has darker markings than the summer form. The larva (caterpillar), known as the southern cabbageworm.
Checkered white populations have drastically decreased in eastern Unites States, and the butterfly is now scarce or extirpated in some areas where it was once common. It appears stable in the west. The cause of the decline is unknown, though habitat loss is certainly a contributor. It is possible that the extremely abundant introduced species cabbage white is displacing native whites, including checkered white. It is also possible that checkered white is a western and midwestern species that only sporadically became abundant in eastern agricultural fields. It remains to be seen whether the decline will continue to spread westward.
Pst on Canada thistle
Visitors to Minnesota’s natural places will occasionally come across a stand of Canada thistle with a few plants that are whitened at the top, appearing bleached. The discoloration is caused by the bacterium Pseudomonas syringae pv. tagetis. It has been called “White‐colour Disease of Canadian Thistle,” “apical chlorosis of Canada thistle,” and “Bacterial Speck”, but it has no widely-accepted common name. It is often referred to in scientific literature as Pst.
Outside of a laboratory, a bacterium is recognized only by the symptoms it produces in its host. Pst produces the substance tagetitoxin, which blocks the production of chloroplasts, preventing photosynthesis. This results in whitened plant growth (chlorosis) on only the upper portion of the plant, stunted growth, fewer shoots, and inhibition of flowering. Pst infects plants in the Aster family, including Canada thistle, common dandelion, common sunflower, common ragweed, giant ragweed, Jerusalem artichoke, and some other plants not found in Minnesota.
Researchers at the University of Minnesota conducted a study in 2002 to assess the viability of using Pst as a biological control agent for Canada thistle.
Orange-gilled Waxy Cap (Humidicutis marginata) is a medium-sized, easily identified mushroom. It is widespread in North America but not common in the Midwest and northeast. It grows on the ground in humus, sometimes on very rotten wood, in coniferous, deciduous, and mixed forests. It may be found singly, scattered, or in small groups. It is edible but insubstantial and watery.
Three varieties are recognized; var. marginata, with an orange cap; var. concolor, with a yellow cap, more common in the northeast; and var. olivacea, with a olive-colored cap, more common in the west. The variety in most common in Minnesota is identified by the bright orange color; the cap that appears watery when wet but is never slimy; and the orange gills that retain their orange color even long after the cap has faded to yellow.
At only one tenth the width of a human hair in length, a crimson erineum mite (Aceria elongatus) is barely visible to the human eye unaided by magnification. Its claws, dorsal shield markings, and other identifying body features are not. Identification in the field is possible only by noting the properties of the abnormal growths (galls) it produces on its host.
Crimson erineum mite is a plant parasite infecting only sugar maple and possibly black maple. It is common in eastern United States and Canada. When injured by a mite, a leaf cell produces a small projection filled with colored fluid on the upper surface. Small patches of these are usually scattered over the leaf surface. They are greenish-white at first, soon becoming crimson or purplish. They reach their maximum extent, and are most noticeable, in summer. The infestation is sometimes abundant and can cause leaf distortion and premature leaf drop.
Photo by Dan W. Andree
At 1¾″ long, eyed click beetle (Alaus oculatus) may be the largest click beetle in our area. With its boldly-outlined eye spots it is certainly the most distinctive.
The body is long, thin, and black, with mottled patterns of minute, whitish scales. The thorax has a pair of large black spots boldly outlined with white. The spots look like eyes and give this beetle its common name.
On the underside, an elongated lobe on one plate fits into a groove in another plate, allowing the insect to produce an audible click. This feature gives the insect family the common name “click beetles”. If put on its back, the beetle uses this click mechanism to catapult itself up to six inches in the air, righting itself and potentially escaping a predator.
Click beetle larvae are called wireworms. Most wireworms eat plant roots, and can be serious agricultural pests. Eyed click beetle wireworms are carnivorous. The feed on the larvae of other insects, especially wood-boring beetles. This makes them a beneficial insect.
Photo by Margot Avey
There are sixteen species of Hericium fungus, four of which occur in North America, three in Minnesota. Comb Tooth (Hericium coralloides) is by far the most common of the three. It is fairly common in northeastern United States and in Minnesota. It is found in late summer and fall in deciduous woodlands and forests, on fallen logs, branches, and dead stumps of hardwoods.
The fruiting body is a loose, open cluster of delicate branches. It is white when fresh, becoming creamy-white to buff or yellowish-tan with age. The branches are themselves again intricately branched and have rows of evenly-spaced spines, like the teeth of a comb, that hang downward. The spines are the spore-producing structures of this fungus, corresponding to the gills on many mushrooms (Agaricales). The flesh is white and edible when young and soft, but the spines become brittle with age.
Comb Tooth is similar in appearance to the other two Hericium species in Minnesota. It is the only Hericium that is intricately branched and has teeth no more than ⅜″ long.
Photo by M.j. Horgan
There are more than 3,000 species of walkingsticks worldwide, 29 species in North America north of Mexico, and probably just 2 species in Minnesota. Northern walkingstick (Diapheromera femorata) is the most common walkingstick in North America and in Minnesota. The extremely long, thin, almost cylindrical body strongly resembles a leafless twig making it invisible to predators.
In Minnesota, the northern walkingstick population fluctuates on a two-year cycle. The odd numbered years are the “boom” years, the even numbered years the “bust” years. They mate in late summer. The female drops eggs to the ground one at a time. During heavy infestations, female egg-dropping can sound like falling rain. The eggs remain on the ground until the second following spring. After almost two years, they hatch between mid-June late July. During the night, the nymph crawls up the first vertical object it encounters. If that is a stem of a shrub or tree, it begins feeding. Otherwise, it returns to the ground and seeks another vertical object.
The other walkingstick known to be found in Minnesota, prairie walkingstick (Diapheromera velii), is very similar in appearance. Northern walkingstick is distinguished by its occurrence in forested habitats, the dilated and banded femur on the middle leg of the male, and the much shorter sensory appendages at the end of the abdomen of the female.
Photo by Bill Reynolds
Minnesotans are seeing the huge influx of painted lady (Vanessa cardui) butterflies in the summer of 2017. Observers from the Twin Cities to Detroit Lakes and Pennington County have reported seeing “15 plus,” “dozens”, “lots and lots,” and “plentiful” painted lady butterflies this year. Lora in Corcoran reports them “swarming the soy bean field across the road.” Ruth in Big Stone County reports seeing “clouds of them.”
Painted ladies are both migratory and cyclic. They overwinter in the southwestern United States and in northern Mexico. They migrate north in the spring in most years, temporarily repopulating the United States and Canada. Some years they do not migrate at all. In years of much rain on the wintering grounds the northward migrations are enormous. They migrate south beginning in August and continuing through November. They are cyclic because some years their populations are large, some years small.
Painted lady butterflies are very similar in appearance to American Lady (Vanessa virginiensis) butterflies. Painted lady is less orange above. The large spot near the tip of the forewing is always white, never pale orange. The black band in the middle of the forewing creates an isolated orange spot. The dark spots on the hindwing are smaller, do not touch, and do not have blue centers. There are four eyespots on the underside of the hindwing.
Photo by Bill Reynolds
Downy yellowjacket (Vespula flavopilosa) is an uncommon, medium-sized, predatory, social wasp. It is found in the northeastern United States from Minnesota to Maine, south to Virginia, and along the Appalachian mountains to northern Georgia. It closely resembles eastern yellowjacket. It is thought by some to be a hybrid between eastern and common yellowjackets. Others suggest that it probably arose as a hybrid but now queens mate with drones of the same species.
The overwintering queen emerges from hibernation in April or May. She builds a nest of 20 to 45 cells and cares for the grubs as they hatch. In about 30 days the workers emerge and take over nest building duties. Through spring and summer the queen produces a large number of worker wasps. In mid-summer, the nest grows exponentially, as more and more workers become available, ultimately with 3,500 to 15,000 cells. Only the new queens survive the winter, hibernating under loose tree bark, in a decaying stump, or in another sheltered location.
In eastern North America, four yellowjacket species, common, downy, eastern, and German yellowjackets, closely resemble each other, making identification difficult. Downy yellowjacket is distinguished from the others by a continuous, uninterrupted yellow band on the face below the compound eye; and by the shape and pattern of black markings on the first and second abdominal segments.