Tent caterpillars: construct their silky tent like nests in early spring in the crotches of trees such as cherry (Prunus) and apple (Malus). They feed during the day, and at night, they return to the tent for protection. Your first line of defense should be to begin looking for these nests in early spring, about the time saucer magnolia (Magnolia x soulangiana) and crabapples are at bud break. Once located remove the nests and burn them, where permitted. Alternatively cut the tent open and hand pick the caterpillars throwing them into a bucket of soapy water. These 2 methods are most effective because large numbers can be removed at once. (Be sure to wait until they have returned to the nest for the evening before removing the nest).
Your second line of defense is spraying them with BT (Bacillus thuringiensis). Check for egg masses in the fall and spring and remove any you may find by scraping the clusters with a knife; prune trees in late fall or early spring also helps to keep populations low. Some natural enemies of tent caterpillars are birds and rodents. If physical and biological measures are not effective, use a pesticide which will have a minimal impact on both you and the environment. Apply dormant oil in late winter to kill the eggs before they hatch. An insecticidal soap is another option for control of the eastern tent caterpillar.
Slugs and Snails: In areas where slugs have posed a problem in the past till the area well or hand dig in the spring the reduce populations. Slugs prefer heavy, wet soils, particularly for laying their eggs. They also like weedy areas with plenty of soil spaces to hide in try to avoid such conditions. Sprinkling sand, ashes, broken eggshells and soot around vulnerable plants is a fairly effective deterrent, but they require constant reapplication (diatomus earth works in the same way). These barriers are scratchy and sharp serving to dry up the slugs mucous glands which are necessary for their movement. Hand picking still remains one of the most effective ways to reduce slug populations. Drop them into a bucket of warm soapy water or squash them under foot. Dusk and overcast days are the best times to go out picking. To encourage ground-living insect predators within the beds try laying down wooden boards. The predators hide under these during the day, emerging at night to perform their duty. As an added bonus slugs and slug eggs also collect there. Scrap them off into a bucket of warm soapy water once a week to further reduce your slug populations.
Viburnum leaf beetles: Only infest viburnums but they can nearly skelatonize the entire shrub. Adult females lay up to 500 eggs on viburnum twigs in summer and early fall. The eggs overwinter and hatch in spring. Larvae feed on foliage until early summer, then crawl down the shrub and pupate in the soil. Adults emerge from the soil in midsummer, feed again on viburnum foliage, and mate. From egg hatch to adult takes just 8 to 10 weeks. Egg-laying sites are easiest to spot when viburnums are leafless. Look for infested twigs between early October and mid-April and prune them out. This is probably the single most effective measure you can take to limit beetle populations.
Cut worms: Are a common pest of many vegetable crops. They consist of the larvae of several species of night-flying moths. Cutworms feed at night and will not generally be observed on plants or on the soil surface during the day, but you will know they are present by their characteristic damage, finding seedlings that have been ‘cut’ off at ground level. If you find this type of damage dig down around these plants to a depth of about 5 cm to find the cutworm(s) and destroy it/them. Cut worms lay their eggs on the soil; weedy areas, fields of grasses or pasture are ideal sites for cutworms to overwinter. Placing protective collars (like toilet paper rolls) around young seedlings is an effective way for the small home gardener to protect their young seedlings against cutworms.
Gypsy Moth: The European Gypsy Moth (Lymantria dispar), so named because of its ability to travel by attaching itself to various objects, is considered a major pest in North America. The caterpillar, or larva stage of the insect, eats approximately 500 species of trees. Broad-leaved trees are preferred, mainly red and white oak, poplar and white birch. The eggs hatch into caterpillars just as the tree buds are beginning to open and feed voraciously for up to 7 weeks. Therefore, it is important to control gypsy moth infestations early in the growing season.
Lily Beetles: eat the leaves, stems, buds and flowers of lilies, fritillaries and other members of the Liliaceae family. They overwinter in the soil and come out early in spring. Do not mistake this beetle for the cardinal beetle which preys on other insects and is normally found on flowers at the edges of woodland. The lily leaf beetles have wings that are shinier with tiny dimples on them; they are more rounded in shape compared to the dull, narrow, flattened and elongated Cardinal beetle. Another difference between the two is their food preference. Lily leaf beetles are herbivores and are usually found on lily plants eating their leaves whereas the cardinal beetles are usually found on tree bark and flowers and feed on flying insects. Lastly, the cardinal beetle has comb-like antennae.
Lily beetles can be difficult to get rid of. Dormant oil may be used in early spring (before leaves are in bud) to suffocate the over wintering adults. Neem oil is also effective when applied to the early stages of larvae. Handing picking, knocking them into a bucket of warm soapy water, still remains the most effective treatment. It can be helpful to place a light coloured material beneath your lilies before picking as they tend to drop off when the plant is disturbed with their black undersides pointing up.
Soft- Scale: are typically found on woody and foliage plants. They feed on the sap causing yellowing of leaves and overall plant decline. They also secrete a sticky clear substance known as honeydew which provides the ideal environment for “sooty mold"; a fungus which can be more damaging than the scale itself. This honeydew also attracts ants which then carry the scale to uninfested plants as well as protect them from natural enemies such as predators and parasites. The first nymphal instar is called a crawler and has functional legs, while the remaining instars are attached to the leaf or twig and (with the exception of green shield scale) do not move.
Dormant oils and contact insecticides can be effective, but only if they are applied to the unprotected crawler stage of the scale. Thus, timing of contact insecticide application is critical to effective control. Parasitic wasps whose adults lay their eggs inside of soft scale may further serve to reduce scale populations. Metaphycus prefers young stages, Encyrtus the adult
Hard- Scale: differ from soft scale in that they generally have two or more generations per year. They do not produce honeydew and typically overwinter as eggs underneath the body of the dead female. (with the exception of euonymus scale which lay their eggs in early spring).They usually appear circular or rounded in shape and their crawlers tend to be less active.
Spider mites: Spider mites are common plant pests. They thrive in hot arid conditions thus irrigation and moisture management can be important cultural controls for spider mites. Symptoms of injury include flecking, discoloration (bronzing) and scorching of leaves. Injury can lead to leaf loss and even plant death.
Natural enemies include small lady beetles, predatory mites, minute pirate bugs, big-eyed bugs and predatory thrips
Aphids: They are small, soft bodied insects with piercing mouth pieces that suck plant juices from a wide variety of plants. They vary greatly in size and colour. Damage includes spotty yellow leaf discolourations, curling or distorted leaves and stunted new growth. As aphids feed they secretesticky substance called honey dew, providing (in humid conditions) the perfect breeding ground for black sooty mold. Insecticidal soaps and dormant oil are some what effective in controlling populations. Spraying them with a fast jet of water is also helpful. Lady bugs are a natural predator.