Cankerworms (inchworms) cause defoliation in shade trees. They are found on elm, apple, hackberry, basswood, oak, boxelder, maple and ash trees as well as shrubs growing beneath heavily infested trees.
Spring and fall cankerworms feed at the same time of year on the same trees causing the same kind of damage.
Large numbers of caterpillars spinning to the ground on silken threads, crawling or falling on picnic tables, doors, walks and/or house siding can create an unpleasant environment.
Cankerworms chew small holes on leaves.
Information source: University of Minnesota Extension
The cecropia moth caterpillar is the largest larva found in Iowa and is commonly seen in late summer throughout the state. Larvae may be seen feeding on the trees and shrubs where they have spent the summer, or they may be found “wandering” across lawns, sidewalks, and driveways.
The caterpillar is about four inches long and nearly 3/4 inch in diameter. The body color is light green with a fluorescent blue tinge. On the top of the body just behind the head are several pairs of large tubercles that look like red, orange or yellow balls covered with black spikes. Along the rest of the length of the body are two rows of yellow spikes and two rows of light blue spikes.
The cecropia caterpillars feed on a wide variety of trees and shrubs, including wild cherry, plum, maple, willow, boxelder, apple, crabapple, lilac, walnut, elm, birch, and poplar. During their life span of approximately 60 days, the caterpillars can devour a lot of foliage. However, caterpillars usually occur in widely-scattered, low numbers and significant defoliation damage is very unlikely except on very small, newly transplanted plants.
In late summer the caterpillar spins a dirty gray or brown cocoon resembling a pod attached to plant twigs or hung between branches. The cocoon is about four to five inches long and an inch or two wide. The insect remains inside this cocoon all winter and the adult moth emerges the following May. The moth is very large and attractive, though they are seldom noticed because they are active at night. The overall wing color is dark reddish-brown. There are black spots near the outer tips of the forewings and a crescent-shaped spot in the center of each wing. The moth’s body is very plump and is covered with long, rust-red hair.
Information source: Iowa State University
Forest tent caterpillars in Minnesota attack a number of broadleaf trees and plants like quaking aspens, balsam poplar, basswood, oaks, ashes, birches, alder and fruit trees.
Feeding damage by these caterpillars slows down the growth rate of deciduous trees.
When target trees are defoliated, forest tent caterpillars may also damage other nearby plants.
Damage can be seen on vegetables, fruit trees and other small fruits, and nursery crops.
They are a nuisance when they are found around buildings or on roads.
The forest tent caterpillar (Malacosoma disstria) occurs throughout most of the United States and Canada wherever hardwood trees are found. This caterpillar rarely feeds on red maple and conifers, such as pine and spruce.
Feeding by forest tent caterpillars generally does not kill deciduous trees, as they can produce another set of leaves during the same season.
Healthy trees can tolerate two to three consecutive years of heavy defoliation.
Trees may be killed if the same tree has been heavily defoliated for four or more years, or when trees become stressed, such as during a drought.
Information source: University of Minnesota Extension
Japanese beetles are an invasive species. Japanese beetles feed on the leaves, flowers or fruit of more than 300 species of plants. Japanese beetle grubs are pests of turfgrass. They chew grass roots, causing the turf to brown and die. Grub-damaged turf pulls up easily from the soil, like a loose carpet. Japanese beetle infestations in Minnesota are mostly found in the Twin Cities metropolitan area and southeast region of the state. There are both nonchemical and insecticide options for managing Japanese beetle adults and grubs.
Japanese beetles are a serious pest of flowers, trees and shrubs, fruits and vegetables, field crops and turf. Adults feed on more than 300 plant species, whereas the grubs feed mainly on the roots of grasses.
Adult Japanese beetles feed on the leaves, flowers and fruits of many different plants. Preferred plants include rose, grape, linden, apple, crabapple, cherry, plum and related trees, birch, elm, raspberry, currant, basil, Virginia creeper, hollyhock, marigold, corn silks and soybean. They skeletonize leaves by feeding on tissue between the major veins giving them a lace-like appearance. Damaged leaves turn brown and may fall off.
Information source: University of Minnesota Extension
Read more about Japanese Beetles.
Japanese Beetles In Minnesota, Japanese beetles (Popillia japonica) are primarily found in the Minneapolis-St. Paul Metropolitan area, and in some areas in southeast Minnesota. Japanese beetles have an exceptionally large host range, feeding on the leaves of over 300 species of plants, including apples, grapes, blueberries, raspberries, roses and plums. Identification Japanese beetles are 3/8…
Information source: University of Minnesota Extension
Polyphemus Moth Larvae reach nearly four inches in length and appear “pushed together” from the ends, making it accordion-shaped. Larvae are fat, pale green, and sparsely covered with hair which is not harmful if touched. They feed on many trees and shrubs including oak, hickory, elm, maple, birch, apple, boxelder, cherry, chestnut, willow, ash, grape, pine, and members of the rose family. The larval period is 48 to 50 days long. In late summer or early fall, the larva spins a rounded, tough, parchment-like cocoon in the tree or shrub in which it has been feeding. It overwinters in this cocoon and emerges the following spring or summer as a very beautiful adult moth.
A common giant silk moth, the male has a wingspan of nearly five inches and the antennae are large and feathery. The wing color is light brown with a gray dusting on the forewing edges and vertical pink lines near the body. Each hindwing has a larger yellow eyespot in a field of dark blue to black. Small yellow eyespots occur in the center of the forewing.
Information source: Ohio State University
Information source: University of Minnesota Extension
