bugs, deciduous trees & shrubs
Birch Leaf Miner
Birch leaf miner larvae tunnel or mine the inside of birch tree leaves, creating brown patches in the leaf tissue. When pulled apart, tiny larvae can be seen between the leaf layers. They do not seriously harm the trees, unless numbers are very large.
Birch leaf miner can be prevented for the summer season with a systemic insecticide be placed in the soil at the dripline of the tree as the tree is leafing out. It will move up to the leaves and kill insects that between the leaf layers. Do not apply to young or newly planted trees. It does not need to be done every year. Birch leaf miner cannot be controlled by contact insecticides.
Lilac Leaf Miner
Lilac leaf miner is similar to birch leaf miner, causing black patches in lilac leaves. Little damage is done to the shrub, but leaves become unsightly.
Lilac leaf miner can be controlled by painting each branch of the shrub between the leaf layers, during that summer. It should be applied to a different area of the bark each year, and should not be done every year. Lilac leaf miner cannot be controlled by contact insecticides.
Poplar Leaf Miner
Poplar leaf miners tunnel or mine the inside of leaves, creating irregular shaped black patches in the leaves. The larvae can be seen between the leaf layers. They do little damage.
Poplar leafminers do little harm other than to appearance. There is no chemical control, as the ends of roots are impossible to find (for soil drench) and the bark too thick for painting. They can do considerable damage but do not endanger the tree.
Cottonwood Leaf Beetles
Cottonwood leaf beetles are small yellow beetles with black heads and seven elongated spots that look like stripes. The larvae are tan with two rows of black spots and black heads. They skeletonize leaves of poplar trees, so only the large veins are left.
Cottonwood leaf beetles can be controlled with a contact insecticide sprayed on the tree when the insects are present. They can do considerable damage but do not endanger the tree.
Leafhoppers
Leafhoppers are similar to white aphids, and are common on hops and Virginia creeper. They suck the sap from the leaves, leaving them mottled with white spots. By late summer the leaves become brown and crisp.
Leafhoppers can be controlled with contact insecticides sprayed on the insects. The insects are often on the undersides of vine leaves, and many vines are against walls and fences, preventing the chemical from reaching them. If a garden hose can be aimed into the foliage it can dislodge many of them.
Box Elder Bugs
Box elder bugs are black beetles with a red V on their backs. They are usually seen on sunny fences or walls of buildings. They are attracted to box elder (Manitoba maple) trees. The small red insects are juvenile.
Box elder bugs do little harm and can be safely ignored. A strong stream of water from a garden hose can discourage them.
Ash Plant Bugs
Ash plant bugs are dark beetles with a yellowish-white triangular marking in their backs. They pierce the leaf tissue and suck liquid from the cells of the leaf, leaving yellow stippling on the upper side and brown spots of excrement on the underside.
Ash plant bugs may be sprayed with a contact insecticide if seen early enough to prevent damage but are not usually noticed until it is obvious. Damage done is not serious.
Stink Bugs
Stink bugs vary in color and what they feed on. Some feed on birch, willow, ash and oak foliage. Others are sucking insects that feed on tomatoes. They all have sturdy bodies with angular shoulders and obvious antennae.
Stink bugs can be controlled with contact insecticides if in large numbers. Use one that is appropriate for the plants affected.
Lace Bugs
Lace bugs are squarish insects with lacy material between the body and wings. The larvae pierce the leaf and suck fluids from it, causing light flecks on the upper side of the leaf. The dark, sticky excrement on the underside of the leaf can be enough to stop the leaves from manufacturing food.
Lace bugs can be controlled with contact insecticides if in large numbers. Use one that is appropriate for the plants affected.
June Bugs
June bugs are black beetles that feed on the foliage of deciduous trees, flowers, weeds and vegetables. The damage they do is minimal compared to that of their larva. White grubs (the larval stage) spend up to three years in the soil, eating the roots of lawns and root vegetables, particularly potatoes.
Do not plant potatoes in an area infected by June bugs. There is no chemical control for potatoes, but lawns can be treated with soil or liquid insecticides appropriate for lawns.
Spittlebug
Spittlebug nymphs cover themselves with a frothy mass of spittle and air bubbles. The female also covers her eggs with froth. Adults resemble brown leafhoppers and are not covered with spittle. Both nymphs and adults pierce foliage and twigs to feed on sap.
Spittlebugs can be controlled with contact insecticides appropriate to the plants affected. Damage is unsightly and occasionally enough to harm the plant.
Rose Curculio
Is a red beetle with a long snout. The adults feed on flower buds. It punctures them and the holes are obvious as the flowers open. They also feed on the tips of new rose shoots, causing them to die. The larvae feed on the reproductive parts of the flowers.
Rose Curculio dusts and sprays are available to control Rose Curculios as they occur.
Aphids
Aphids are small green or black insects with bodies like small balloons. They can be found on the stems, flower buds or new leaves and can attack almost any plant by sucking sap from the tissue. Leaves often curl over and are stunted, and a sticky residue called honeydew can be a nuisance. Ants are often seen in these areas as they like the sweet honeydew.
Aphids can be controlled with contact insecticides but they will kill only those insects they touch. The insects are often inside a rolled up leaf and contact is unpredictable. There are many generations, so it is impossible to eliminate them all. A frequent, hard spray of water will keep them somewhat under control.
Wooly Elm Aphids
Wooly elm aphids secrete a powdery white waxy substance and honeydew that makes the leaves very sticky. Leaves curl and become very unsightly but little damage is done to the tree. Later in the summer they migrate to saskatoon, their alternate host. They live in the roots and can damage young seedlings.
Wooly elm aphids are difficult to kill with chemicals as the aphids are curled up inside the leaves and are not reached by contact insecticides. Dusts may be used in the soil of saskatoons if aphids are present, but be sure they are safe for food plants.
Aphids on Cranberry Bushes
Aphids on cranberry bushes are small green or black insects with bodies like small balloons. They leave a purplish lumpy look to cranberry leaves. The insects underneath the leaves do relatively little damage.
Aphids on cranberry can be hosed off with a strong spray of water. Contact sprays suitable for fruiting plants can be used.
Aphids on Honeysuckle Shrubs
Aphids on honeysuckle shrubs (not climbers) are a particular type that live on the tops of the leaves, causing tips to fold up lengthwise and curl over like a shepherd's crook (witch's broom).
Aphids on honeysuckle shrubs cannot be controlled with chemical sprays, as the spray cannot contact the insects inside the folded leaves. Pruning the tips whenever aphids are seen, and removing them from the garden, is the only control.
Aphids on Willows and Poplars
Aphids on willows and poplars are large, black insects that cluster along the branch tips. They suck sap from the new wood that is easy to penetrate, and will cause small branch ends to die but do no major harm to mature trees.
Aphids on young trees should be sprayed with a contact insecticide when they are present. It may have to be repeated if more are seen later. Mature trees will not be harmed by the loss of twigs on the ends of the branches.
Aphid Skins
Aphid skins can look like small, elongated, white insects at a glance, but they are the skins that are left behind as the insects outgrow them. They do, of course, indicate that aphids are or have been present, but nothing need be done unless actively feeding insects are seen.
Aphid skins need no control unless live aphids are also present.
Thrips
Thrips are minute black insects which particularly attack green ash trees and others of the same family. They are long and narrow and leave speckles on the leaves, which die prematurely.
Thrips can be controlled with contact insecticides when insects are present.
Willow Sawfly Larvae
Willow sawfly larvae are grayish caterpillars with many black spots, that feed on leaves. There are two generations per year.
Willow sawfly larvae can be picked off or controlled by contact insecticides when present if in large numbers.
Nematus Sawfly Larvae
Nematus sawfly larvae on poplar trees are black with yellow spots . The young larvae eat the tissue between the veins of leaves close to the ends of branches. Older larvae eat all but the largest mid-vein.
Nematus sawfly larvae can be controlled by contact insecticides if present in large numbers.
Pear Slugs
Pear slugs are small, dark, slimy larvae of a sawfly. They feed on leaf tissue, leaving dry areas between the veins. They are common on purple leaf plum and cotoneaster. They are most active in the fall, so plant growth is not affected.
Pear slugs can be controlled with contact insecticides if numbers are excessive.
Spiny Elm Caterpillars
Spiny elm caterpillars are dark blue with orange spots and black bristles. They eat leaves of elm, willow, and aspen and can defoliate smaller trees. They are the larvae of the mourning cloak butterfly.
Caterpillars that are exposed can be killed with contact insecticides, but those rolled inside leaves will not be affected if the spray cannot come in contact with them.
Spring and Fall Cankerworms
Spring and fall cankerworms are small caterpillars, usually yellowish-green, that chew small holes in new Manitoba maple, elm, birch and fruit tree leaves. As feeding continues, the holes gradually enlarge until only leaf veins are intact. Trees produce another set of leaves a few weeks later, but severe infestations can weaken a tree. The caterpillars drop on silken threads to move to new areas. They move with a looping motion. Mature larvae of spring cankerworms overwinter in the soil and pupate in the very early spring, emerging soon to begin feeding. Fall cankerworm eggs overwinter on trees and hatch in late May to begin feeding.
Cankerworms that are exposed can be killed with contact insecticides, but those rolled inside leaves will not be affected if the spray cannot come in contact with them. A biological insecticide controls them when they are young and feeding.
Ugly Nest Caterpillars
Ugly nest caterpillars on chokecherry, pincherry and related trees. The adult is a reddish-orange moth and the larva is a tan caterpillar with a black head. They live in silk-covered tents which are very unsightly.
Ugly Nest caterpillars that are exposed can be killed with contact insecticides, but those rolled inside leaves will not be affected if the spray cannot come in contact with them.
Red-Cheeked Looper
Red-cheeked looper is a slender, dull red caterpillar that chews holes in the leaves of birch, willow and dogwood. It does not do enough damage to cause concern. The adult is a gray moth.
Red-cheeked loopers can be controlled by a contact insecticide when they are present, if damage is enough to warrant it.
Hydria Undulata
Hydria undulata is a light purple caterpillar with a brown head. It defoliates willow and poplar, but causes little damage. The adult is a small grayish-yellow moth.
Hydria undulata can be controlled by a contact insecticide when it is present, if damage is enough to warrant it.
Lithophane Amanda
Lithophane amanda is a pale green caterpillar with a bluish-green head, covered with tiny white spots and a lengthwise yellow stripe. It feeds on birch and willow leaves, but does minimal damage. The adult is dull, gray-brown moth.
Lithophane amanda can be controlled by a contact insecticide when it is present, if damage is enough to warrant it.
Wooly Bear Caterpillars
Wooly bear caterpillars are black with a wide yellow band in the centre. The adult is a tan tussock moth. The larvae eat leaves of willow, Manitoba maple, birch and aspen, but cause little damage.
Wooly bear caterpillars can be controlled by a contact insecticide when it is present, if damage is enough to warrant it.
Giant Silkworm Caterpillars
Giant silkworms are large, pale green and each segment has six bristled pink tubercules. The head is blue-green and there is a pale yellow line along the side of the body. They defoliate birch, bur oak and willow.
Giant silkworms can be controlled by a contact insecticide when they are present, if damage is enough to warrant it.
Poplar Bud Gall Mite
Poplar bud gall mite creates cauliflower-like galls (swellings) in new leaf clusters. They are caused by minute mites which trigger gall growth in the tree. A gall is the tree's way of protecting itself from an invader. Ends of branches beyond galls may die because the gall can constrict a branch and water cannot move along the branch.
Poplar bud gall mite cannot be controlled with a chemical. Pruning off the growths is the only control.
Willow Pinecone Gall
Willow pinecone gall is cause by a midge. Swellings on the ends of native willows look like pine cones. A gall is the tree's way of protecting itself from an invader. Ends of branches beyond galls may die because the gall can constrict a branch and water cannot move alongthe branch.
Willow pinecone gall cannot be controlled with a chemical. Pruning off the growths is the only control.
Rose Gall
Rose gall affects shrub roses, most commonly Hansa. It is caused by a specific wasp that secretes a chemical which causes the stem to enlarge. A gall is the tree's way of protecting itself from an invader. Ends of branches beyond galls may die because the gall can constrict a branch and water cannot move along the branch.
Rose gall cannot be controlled with a chemical. Prune the canes down to well below the gall and remove from the garden.
Chokecherry Midge
Chokecherry midge causes fruit that is hollow inside, as the larva of the midge live in the fruits as they are developing. It can also affect saskatoons.
Chokecherry midge cannot be controlled with a chemical, as the insect is inside the fruit and any chemical affecting it would be eaten by those that eat the fruit (animals and birds as well as people).
Willow Redgall
Willow redgall cause fleshy, round, red swellings in the leaves of willow trees. They are caused by a sawfly which inserts the eggs into the fleshy layers of the leaves.
Willow redgall does no harm to trees other than appearance. They are unsightly but cause no damage. There is no chemical control.
Eriophyid
Eriophyid mites cause numerous small yellow galls on the leaves of mountain ash.
Eriophyid mite galls are unsightly but cause no damage. There is no chemical control.
Parathecabius
Parathecabius galls are caused by an aphid. The swellings look like strings of beads at the edges of the leaves of balsam poplar.
Parathecabius galls cause the leaves to be deformed but there is no danger to the tree. There is no chemical control.
Box Elder ( Manitoba Maple ) Leafgall
Box elder ( Manitoba maple ) leafgall is caused by a midge (a tiny, slender fly) that rolls the leaves and causes elongated swellings on the edges.
Box elder ( Manitoba maple ) leafgall causes the leaves to be deformed but there is no danger to the tree. There is no chemical control.
Psyllid Galls
Psyllid galls on rose leaves are hairy swellings that are a curiosity but do no damage.
Psyllid galls on roses cause the leaves to be deformed but there is no danger to the plants. There is no chemical control.
Oystershell Scale
Oystershell scale resembles tiny oystershells in clusters, about 3mm.long. It is typically on dogwoods. Scale is a hard covering over the eggs of an insect which protects the eggs until they hatch. Crawlers emerge, and move to leaves for a short time in the summer. They spend the rest of their lives immobile on twigs.
Oystershell scale cannot be controlled with chemicals. Cutting off affected branches can be effective if infestation is light, but if they are on many branches or return after several prunings, removing the tree or shrub may be the only effective control.
Lecanium Scales
Lecanium scales appear to be hardened dark brown shells 3-6 mm diameter. It is common on roses. Scale is a hard covering over the eggs of an insect which protects the eggs until they hatch. Crawlers emerge, and move to leaves for a short time in the summer. They spend the rest of their lives immobile on twigs.
Lecanium scale cannot be controlled with chemicals. Cutting off affected branches can be effective if infestation is light, but if they are on many branches or return after several prunings, removing the tree or shrub may be the only effective control.
Scurfy Scale
Scurfy scale is a grayish-white oval pointed at one end. It is usually in dense clusters, and is common on elms. Scale is a hard covering over the eggs of an insect which protects the eggs until they hatch. Crawlers emerge, and move to leaves for a short time in the summer. They spend the rest of their lives immobile on twigs.
Scurfy scale cannot be controlled with chemicals. Cutting off affected branches can be effective if infestation is light, but if they are on many branches or return after several prunings, removing the tree or shrub may be the only effective control.
Cottony Scale
Cottony scale produces white, waxy secretions which cover their bodies. It is common on maple trees but can infect many others.
Cottony scale cannot be controlled with chemicals. Cutting off affected branches can be effective if infestation is light, but if they are on many branches or return after several prunings, removing the tree or shrub may be the only effective control.
Bronze Birch Borer
Bronze birch borer is a slender, long beetle, olive green to black, that lays eggs in weakened or dying wood. The creamy white larvae excavate tunnels beneath the bark, producing a series of bumps. The adults chew D-shaped holes through the bark. Upper branches of trees die as the tops are affected the most. This insect is not commonly the cause of tree top death in our area. Lack of water in the fall is a much more common reason for the top of the tree not leafing out in the spring.
Bronze birch borer cannot be controlled by a chemical. Pruning the top back to healthy growth is the only control.
Western Ash Bark Beetles
Western ash bark beetles affect green ash and related trees, but not mountain ash, which are a different family. Trees under stress are most likely to be affected. Leaves on an affected tree branch will wilt suddenly and later die. A ring of small holes like a bracelet around the branch indicates beetle infection.
There is no chemical control for western ash bark beetle . Infected branches should be removed as soon as seen and sealed in a plastic bag before discarding.
Poplar Borers
Poplar borers are long, slender gray beetles stippled with small brown dots. They have very long antennae. They feed on poplar foliage, then cut crescent-shaped notches in the bark where they deposit eggs. The larvae are creamy white grubs that bore into the heart of the tree, ejecting sawdust as it occurs. Trees infested with poplar borers exude large amounts of brown sap. This does not kill the tree but it weakens it so it can break during windstorms. Woodpeckers are attracted to the tree in search of insects, and ants are attracted to the sap.
There is no chemical control for poplar borer. Affected branches should be removed. Areas where sap is flowing can be cleaned out and left open to heal.