Monthly Archives: December 2015

Late Oyster Mushroom (Panellus serotinus)

Late Oyster Mushroom

Late Oyster Mushroom (Panellus serotinus) is common, widespread, and aptly named. It appears in the late fall with the onset of cold weather. It is found singly or in overlapping groups on the trunk or a large branch of a dead and decaying tree. It usually occurs on a hardwood, especially black cherry, but occasionally also on a conifer.

There is often no stalk. When there is a stalk it is short, thick, and attached at the side. The cap is kidney-shaped or semi-circular. It is downy and often flushed with violet when young, becoming hairless and olive-green to yellowish-green as it ages, eventually turning yellowish-olive or light brown when mature. The edges are curled under at first but flatten out with age. The gills are yellowish or orangish but fade with age. It is edible but has a mediocre taste and becomes bitter as it ages.

Oak leaf gall midge (Polystepha pilulae)

oak leaf gall midge (Polystepha pilulae)

Many insects form detachable galls on oak. All but two of these are cynipid wasps. The two exceptions are the oak gall midges Polystepha pilulae and Polystepha globosa.

Oak leaf gall midge (Polystepha pilulae) is a long-legged, 1 ⁄16″ to ⅛″ long, mosquito-like fly (midge). Adults are impossible to identify by appearance in the field. However, the species can easily be identified by the gall it produces. Galls appear always on the upper surface of northern pin oak, northern red oak, and possibly black oak leaves. They are hard, 1 ⁄16″ to 3 ⁄16″ in diameter, and irregular in shape. They are green when they first appear in the spring, soon turning red or magenta. As they age they become brown and crusty. They can be easily detached from the leaf surface.

Oak leaf gall midge (Polystepha globosa) forms similar spherical galls on the undersurface of the leaves of black oak and possibly other oaks in the red oak group.

Grape phylloxera (Daktulosphaira vitifoliae)

grape phylloxera

Grape phylloxera (Daktulosphaira vitifoliae) is a very small, soft-bodied, aphid-like insect. It has a complex life cycle with up to eighteen stages and four distinct forms.

Grape phylloxera is a pest of grapevines around the world. It originated in southeastern United States, where some American grape species developed resistance or tolerance to it. It was introduced into France in 1860 when infected vines were imported for their resistance to powdery mildew. In the next 40 years the pest destroyed nearly two-thirds of wine grape vineyards in Europe.

Grape phylloxera adults are difficult to identify because of their extremely small size. They are usually identified by the galls they produce on the roots and leaves of grape plants. Galls on the tips of rootlets are yellowish-brown, hook-shaped swellings. Galls on larger roots are rounded, wart-like swellings. Galls on the underside of leaves are small, green, rough, and more or less globular.

Frosted whiteface (Leucorrhinia frigida)

frosted whiteface

Frosted whiteface (Leucorrhinia frigida) is a small “skimmer” dragonfly. It is fairly common in the upper Midwest, more common in the northeast. It is found from mid-May to mid-August at the edges of boggy or marshy ponds and lakes. It forages by perching on low plants at the waters edge. While the female deposits her eggs her mate will guard her by snatching and holding a rival male until the eggs are laid.

Whitefaces (genus Leucorrhinia) are identified by their white face, small black patch at the base of each wing, and black legs. Frosted whiteface males are distinguished by a brown thorax with no red markings; abdominal segments one through four covered with a whitish, waxy bloom (frosted); and the region of the wing just beyond the forewing triangle having just two rows of cells, not three. Females and juveniles are difficult to distinguish from other whitefaces.

Robin’s carpenterworm (Prionoxystus robiniae), A Very Large Micromoth

Robin’s carpenterworm

Photo by Bill Reynolds

Micromoth is an artificial grouping having no taxonomic equivalent. The name suggests that these are small moths, and indeed most have a wingspans of less than ¾″. However, micromoths are not distinguished by size but by wing venation and the female reproductive tract.

Carpenterworms are wood-boring micromoths. The caterpillars feed by boring into the cambium layer of a tree. This creates galleries and tunnels under the outer bark that decrease the value of the wood and can sometimes kill the tree. Wood has little nutritional value. As a result, the caterpillars take 3 or 4 years to complete their life cycle. They pupate in the spring of their final year and emerge as adults between May and July.

Robin’s carpenterworm (Prionoxystus robiniae) is a medium-sized moth but a very large micromoth. Adults are 11 ⁄16″ to 1¾″ long with a wingspan of 17 ⁄16″ to 3⅜″. They are similar in size and appearance to sphinx moths and are often misidentified as such. They are distinguished by their large size, heavy body, abdomen that extends well beyond the hind wings, light gray wings with a net-like overlay of thin dark lines, accessory cell and 2 complete anal veins on the forewing, 3 anal veins on the hindwing, and yellowish-orange patch on the hindwing of the male.

Rattlesnake master (Eryngium yuccifolium var. yuccifolium)

rattlesnake master

Rattlesnake master (Eryngium yuccifolium var. yuccifolium) is a common plant of native tallgrass prairies in the eastern United States. Southeastern Minnesota is the northwest extent of its natural range, but very little tallgrass prairie remains in the state. This habitat loss led the Minnesota DNR to list it as a special concern species in 1984.

The common name is derived from its traditional use by Native Americans to treat rattlesnake bite. The plant was also used as a diuretic, a sedative, a pain reliever, a tonic, and for cordage.

This plant is easily identified. The waxy, bluish-green stem and foliage; stiff, grass-like leaves with widely scattered spiny or thread-like teeth; and white, spherical flower heads, combine to create a unique appearance. There are no similar species in Minnesota.

Southern red-backed vole (Myodes gapperi)

southern red-backed vole

Photo by Kirk Nelson

There are six species of voles found in Minnesota. Southern red-backed vole (Myodes gapperi) is one of the smallest. It is common in moist deciduous, coniferous and mixed forests with stumps and logs for ground cover. It is usually the most common rodent in cedar, tamarack, and black spruce swamps. It is active both during the day and at night but more often at night. It is solitary, not forming colonies or pair bonds. It forages mostly on the ground but also in trees. This is the only vole in Minnesota that is a good climber of trees.

Southern red-backed vole is distinguished from mice by a stouter body; shorter, hairy tail; smaller ears and eyes; and molars with high crowns and angular cusps. It is easily distinguished from other voles by the gray sides and reddish back.