Category Archives: Insects

Toothed somberwing (Euclidia cuspidea)

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toothed somberwing

Toothed somberwing (Euclidia cuspidea) is common and widespread across North America from the east coast to the Rocky Mountains. In Minnesota, it is found from mid-May to early July in meadows and in woodland edges and openings with long grass.

It is active both day and night. When flushed from vegetation it flies rapidly for about 20 yards then drops to the ground. It rests with the wings held flat and the hindwings usually concealed. It is attracted to light.

This is a stout, medium-sized moth. The adult is about ⅞″ long and has a wingspan of 1⅛″ to 17 ⁄16″. It is distinguished from similar moths by dark brown triangular spots on the forewing of the adult, and by the presence of reduced leg-like structures on the fourth abdominal segment of the caterpillar.

http://minnesotaseasons.com/Insects/toothed_somberwing.html

Japanese beetle (Popillia japonica)

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Japanese beetle

Japanese beetle (Popillia japonica), native to northern Japan, was first found near Riverton, New Jersey in 1916. Two years later attempts to eradicate it by the USDA failed. It had become established — the population was too large for attempts to control it to be successful. It is now widespread across North America, reported in all of the contiguous 48 states except for Florida. It is well established from Maine to Minnesota south to Arkansas and Georgia.

Japanese beetle is a destructive pest in North America where it has no natural enemies. The larvae feed on roots of grass and other plants, causing damage to lawns, parks, golf courses, and pastures. Adults feed on leaves, flowers, and fruits of several hundred species of plants, including fruit trees, ornamental trees, shrubs, vines, field crops, and vegetable crops. They skeletonize leaves by eating the soft tissue but leaving the larger veins. They have caused 50% to 90% defoliation of birch and cottonwood trees in some neighborhoods of the Twin Cities.

Japanese beetle is a colorful, medium-sized, scarab beetle. It is identified by a metallic green head and thorax, iridescent. bronze or coppery wing covers, and white tufts of hairs at the sides and end of the abdomen.

http://minnesotaseasons.com/Insects/Japanese_beetle.html

Oak leaf gall midge (Polystepha pilulae)

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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.

http://minnesotaseasons.com/Insects/oak_leaf_gall_midge_(pilulae).html

Grape phylloxera (Daktulosphaira vitifoliae)

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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.

http://minnesotaseasons.com/Insects/grape_phylloxera.html

Frosted whiteface (Leucorrhinia frigida)

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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.

http://minnesotaseasons.com/Insects/frosted_whiteface.html

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

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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.

http://minnesotaseasons.com/Insects/Robins_carpenterworm.html

Oak flake gall wasp (Neuroterus floccosus)

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oak flake gall wasp

There are over 750 species of gall wasps (Family Cynipidae) in North America. They are all tiny and look pretty much alike. Fortunately, most can be identified by the appearance, location, and host species of the abnormal growths (galls) their larvae produce.

Oak flake gall wasp (Neuroterus floccosus) galls are found on the underside of leaves of bur oak and swamp white oak. They occur singly though there are usually several galls on any one leaf. They are hemispherical, thickly hairy, and ⅛″ to 3 ⁄16″ in diameter including the hairs. The hairs are white at first but soon turn brown. Each gall contains a single chamber and a single wasp larva. It is revealed on the upper leaf surface as a smooth blister-like bump.

http://minnesotaseasons.com/Insects/oak_flake_gall_wasp.html

Pure green augochlora (Augochlora pura)

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pure green augochlora

There are more than 2,000 living species of sweat bee (Family Halictidae) worldwide. They are so named because they are attracted to the sweat of humans. Fortunately, they seldom sting and when they do the sting is minor.

There are four species of Augochlora in the United States, only one of which is found in Minnesota. Pure green augochlora (Augochlora pura) is a moderately-sized, solitary, metallic green sweat bee. It is very common in the eastern half of North America west to Minnesota. It is found from April to October in woodlands and nearby thickets and pastures.

The overwintered mated female emerges in April. Using an existing insect burrow in dead wood as a starting point, she digs a nest consisting of many branched burrows. She places a pollen ball and nectar in each burrow then lays a single egg on the pollen ball. The first generation offspring emerge as adults in June. By the end of June they have constructed their own nests. The larvae or pupa of the last generation overwinter and emerge as adults the following spring. Adult females overwinter beneath rotting logs in a state of diapause. Males die in the fall.

Sweat bees are identified by a short tongue with a short, pointed last segment; single groove below the base of each antenna; lobe at the base of the hindwing longer than the submarginal cell; and basal vein on the wing strongly arched. Pure green augochlora is distinguished by the completely bright metallic green or coppery body; abdomen not conspicuously striped; dark brown, oval-shaped structure at the base of each wing; wing with three submarginal cells, the first longer than the third; marginal cell of the wing squared off at the end; and upper margin of the plate on the upper lip intruded upon by lobes of the plate above it.

http://minnesotaseasons.com/Insects/pure_green_augochlora.html

Four-spotted skimmer (Libellula quadrimaculata)

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four-spotted skimmer

Four-spotted skimmer (Libellula quadrimaculata) is common, widespread, and misnamed.

Eight-spotted skimmer has two large spots on each wing for a total of eight. Twelve-spotted skimmer has three large dark spots on each wing for a total of twelve. Four-spotted skimmer has two small dark spots on each wing and one large spot on each hindwing for a total of ten. A more appropriate name might be ten-spotted skimmer (Libellula decamaculata).

Four-spotted skimmer is an early season, medium-sized skimmer. It is found from mid-May to September at the edges of boggy lakes and ponds, fens, and slow streams. It is usually seen perched at the top of a tall emergent plant or a weed, often far from water.

It is easily identified up close by the two dark spots on the leading edge of each wing. It is further distinguished by the bright yellowish-brown color on the thorax and front half of the abdomen of juveniles, amber streak with yellow veins at the leading edge of each wing on juveniles, black patch at the base of the hindwing, and narrow yellow stripe on each side of the abdomen. Unlike other skimmers, the female abdomen is tapered like the males, not parallel-sided.

http://minnesotaseasons.com/Insects/four-spotted_skimmer.html

Elm sawfly (Cimbex americana)

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elm sawfly

There are about 9,000 living species of sawflies worldwide. Elm sawfly (Cimbex americana) is the largest sawfly in North America. Adults are found in woodlands across the continent from mid-May to mid-August. As the common name suggests, they feed mostly on elm and willow, but also other hardwoods including maple, birch, and American basswood. Larvae feed on the leaves. Adults use their powerful mandibles to cut horizontal gashes in the bark of twigs and small branchlets in order to feed on sap. They sometimes girdle the limb, causing it to die. They can cause sporadic defoliation but are not considered forest pests.

Sawflies are not flies. True flies (order Diptera) have just one pair of wings. Sawflies have two pairs of wings and are more closely related to ants, bees, and wasps (order Hymenoptera). Adults are distinguished by the parallel-sided body (not waisted like a wasp), and by special structures that help hold the forewings in place when at rest. Larvae are distinguished by six or more pairs or leg-like structures on the abdomen, and a smooth head with no cleavage line.

Elm sawfly is identified by the large size and orange, slightly clubbed antennae with 7 or fewer segments.

http://minnesotaseasons.com/Insects/elm_sawfly.html