Photo by Alfredo Colon
Long-tailed dance fly (Rhamphomyia longicauda) is a small, black, long-legged fly. It is commonly found from May to July in deciduous woods near water. The wings are long and black. The head is round with large bright orange or red eyes. On the female, the middle and hind legs have a fringe of long, black, bristly hairs.
Every evening around sunset, males and females collect in same-sex swarms. Females and fly up and down, the behavior that gives this family its common name “dance-flies”. Females cannot hunt for prey. They receive protein from males as gifts in exchange for copulation. They swallow air, filling and extending their abdomen outward, saucer-like, falsely signaling males that their eggs are nearing maturity. The long hairy legs wrap around the abdomen, making it appear even larger. Males are attracted to females that have largest swollen abdomens and hairiest legs. An individual will break off and join the other swarm to select a mate.
Photo by Alfredo Colon
Colorado potato beetle (Leptinotarsa decemlineata) is relatively small for a beetle but relatively large for a leaf beetle. Adults are ¼″ to 7 ⁄16″ long and about ⅛″ wide. The body is oval when viewed from above and dome-shaped when viewed from the side. The wing covers are pale yellow with five black lines on each side. The are no similar species in Minnesota.
Prior to European settlement, the Colorado potato beetle was found only in Colorado and neighboring states. The potato was introduced into North America in the 1600s and began to be widely grown in the early 1700s. By 1840 the potato reached the insects home range. By 1859 the insect had switched to the potato as its preferred host, and by 1874 it had spread all the way to the east coast. It is now present across North America, Europe, and Asia.
Colorado potato beetle is a serious crop pest to potato growers. The insect rapidly evolves resistance to chemical pesticides. Many insecticides that once successfully controlled the beetle are no longer effective.
Photo by Alfredo Colon
Four-lined plant bug (Poecilocapsus lineatus) is a small, soft-bodied, colorful, true bug. It is common in northeastern and midwestern North America, including Minnesota. It is easily identified by the bright yellow or green body with four black stripes and the orange head. It can be seen from May to July in meadows, gardens, agricultural fields, and around homes.
Four-lined plant bug is considered a pest due to the damage it causes to ornamental plants. Adults and larvae feed on the leaves of herbaceous plants, especially those in the mint and aster families. Leaf damage appears as small, 1 ⁄16″ or less in diameter, light or dark spots on the leaf surface. The color of the spot varies with the species of the host plant. The spots are collapsed leaf tissue which eventually falls out leaving small holes. Larvae cause more leaf damage than adults.
Photo by Dan W. Andree
Six-spotted tiger beetle (Cicindela sexguttata) is a small predaceous, tiger beetle. It is probably the most common species of tiger beetle in eastern North America, possibly the most common on the continent. It is found in the southern two-thirds of Minnesota. Adults and larval burrows are very often seen on paths in the woods. Six-spotted tiger beetle can be thought of as a woodland path species.
The head and body are shiny, iridescent, and usually metallic green, occasionally blue. Flashy tiger beetles (subtribe Cicindelini) are usually identified by the color and pattern of marks on their wing coverings. The common name of this species comes from white spots on the wing covers. There are usually six small spots, often eight, rarely ten, and occasionally none.
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.
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 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.
Photo by Christa Rittberg
With 7,003 species in 530 genera worldwide, robber flies are one of the largest and most abundant families of insects alive today. Bee-like robber flies, as the common name for the genus suggests, resemble bees. There are 240 species of bee-like robber flies, 62 species in North America north of Mexico. Few of the species have been given a common name. Laphria sacrator is one of several species famous for being a bumble bee mimic, so “bumble bee mimic robber fly” will stand in for the common name.
Bumble bee mimic robber fly (Laphria sacrator) is a short, robust, medium-sized, bee-like robber fly. It is fairly common in northeastern and north-central United States, including Minnesota. It has a stout thorax and a short abdomen, both partially covered with long yellow hairs making it resemble a bumble bee. It is one of the hairiest of the bee-like robber flies. Adults are ⅝″ to 1″ long.