Common Insects In The Garden
Aphids
These tiny (1/8 inch long), green, brown, black, white, or pink insects are among the most common in any garden. Small populations do little to no damage in the garden and can be easy to control with a spray of water from the hose. However, when conditions are favorable, the population can explode overnight. Large populations can suck enough juice from the plant to cause leaves and flowers to deform, turn yellow, and/or drop. Secondary problems often follow aphid infestations. Aphids excrete a sugary substance which attracts ants. The ants in turn "farm" the aphids, infesting new parts of the plant or garden. This same sugary excretion also falls to the lower leaves and becomes a site for Sooty Mold to grow, giving the plant a black, dirty appearance. Aphids can also transmit diseases from plant to plant.
Controls: For small infestations control by spraying the plant with a strong stream of water. Larger infestations can be controlled with Insecticidal Soap or insecticides containing Pyrethrins or acephate (Orthene®).
Snails & Slugs
Evidence of these pests include elongated holes in leaves, partially eaten flowers, and shiny silvery tracks left on the leaf and stem surfaces. Snail damage varies from caterpillar damage in that the holes appear primarily in the centers of the leaves, not along the edges or leaf margins. Slug damage also appears in the center of the leaves but typically the papery tissue of the back leaf surface still remains. These pests are most active at night or on cool, overcast days. During sunny or hot days, they hide in cool, damp areas in the garden, under pots, or in groundcover.
Controls: Since these pests are not fast moving, nighttime harvesting is easily done. For those that would rather not handle the slimy pests, chemical controls are very effective. Baits and controls come in a variety of forms from pellets, meals, and granulars to thick, sticky liquids. Each has its benefits: all should be used with caution around pets and children. Organic solutions include beer traps, protecting critical areas with copper mesh, and diatomaceous earth.
Thrips
These very small (1/25th inch), white or yellow bodied insects with brown or black wings are barely visible. These insects feed by rasping through the plant tissues and sucking the cell sap that is released. Signs of their presence are typified by bleached and flecked foliage which has a silvery-tan coloration. Small, black, sticky excretions are also very typical. Infestation on flower or leaf buds will cause malformation or bud death. In our warmer climate, it is not uncommon to find this insect on the plant nearly year round. Unchecked or controlled infestations can severely stunt or even kill the plant.
Controls: These insects are easier to prevent than control. On occasion, spray down the foliage of the shrubs and small trees in your garden with a stream of water. This will keep the plant free from dirt, dust, and control exploding populations. Chemical controls include the use of Horticultural Oil and an insecticide containing acephate (Orthene®). We commonly recommend combining the use of these two products.
Spider mites
This family of mites are major pests in both the home and garden. They suck the sap from the leaves and buds causing discoloration and malformation. Evidence of their presence usually includes yellow stippling, a dusty or dirty appearance to the leaf, and the presence of fine web like material on the underside of the leaves. The most common mites attack plants that are in hot, dry conditions which have little air movement.
Controls: Often you can prevent infestation of your house plants by increasing the air flow and humidity levels around your plants. This means opening a window and misting your plants. Outdoors, you can do the same thing by thinning your plants and occasionally hosing down your plants. If your plants become infested, you can control them with the use of horticultural oil, a miteicide containing hexakis, or insecticides including Isotox® or Diazinon.
White Flies
These small, white, four winged "flies" can cause yellow mottling in leaves. Both the pinhead sized larvae and the adults feed by sucking the sap from the cells on the undersides of the leaves. Typically, you will first notice the white flies when they take flight as you brush against or move the plant. This is another insect that excretes a sugary substance that will collect on the lower leaves and become a host for sooty mold.

 
Controls: Control can be accomplished with Insecticidal Soap or with insecticides which contain Pyrethrins, Acephate (Orthene®), or carbaryl (Sevin®). There are also sticky pheromone traps that will attract and capture these insects.
Mealy Bugs
These small, yellowish green to brown insects produce a white, cottony looking, protective, waxy coat that makes them similar in appearance to Cottony cushion Scale and Woolly Apple Aphids. They congregate in the branch crotches, along the stems, under the leaves, and on soft new growth. Heavy infestations can cause new growth to emerge deformed; eventually, they can kill small plants and portions of larger plants. The excretions of these insects are high in sugar. This sugary excretion also falls to the lower leaves and becomes a site for Sooty Mold to grow, giving the plant a black, dirty appearance.
Controls: Control of these insects is best done with a combination of horticultural oil and an insecticide like malathion or diazinon.
Scale
There are as many different types of scale as there are plants that host them. They can be found on the stems and branches, undersides of leaves, or on the trunks of young trees and shrubs. These small, soft bodied insects emerge form their eggs in spring to mid summer. These crawlers find a satisfactory place on the plant and make it their home. They pierce the cells and feed on the sap. Soon after settling in, their legs atrophy and they develop a hard shell of waxy material over their backs. This makes them immobile. Secondary problems often follow scale infestations. Scales excrete a sugary substance which attracts ants. The ants in turn "farm" the Scale and infest new parts of the plant or garden. This same sugary excretion also falls to the lower leaves and becomes a site for Sooty Mold to grow, giving the plant a black, dirty appearance
Controls: The waxy layer which covers these insects also protects them from insecticides. Use a horticultural oil to control the adult populations throughout the year. Combine the oil with an insecticide, such as, Orthene®, Sevin®, or malathion in spring and early summer to control the crawlers.
Leaf Minors
These light green to silvery tunnels that wind themselves through the leaves are dug by the larvae of some flies, moths, beetles or sawflies. Eggs are laid inside the leaves in early to mid spring. After hatching, the larvae feeds within the leaf until it is time to pupate. Pupation occurs within the leaf or in the soil beneath the plant. When the adults emerge, the cycle begins again. Some adults will also feed on the plant.

 
Controls: Natural control for these insects is difficult. For light infestations, you can remove affected leaves and discard them. Chemical control is typically aimed at the emerging adults. Since the larvae is well protected within the leaf. Contact your local cooperative extension office for emergence times for your area. For non-fruit bearing plants you can control the larvae with a systemic insecticide like Isotox®.
Leaf Roller
This family of caterpillars feed on both the leaves and flower buds. The 1/2-3/4 inch long, green caterpillars protect themselves from birds and other predators by rolling the leaf around them and tying it shut with their silken web. They feed inside the rolled leaves. These insects are typically found only on shrubs and trees. Though these insects are common in many gardens, extremely heavy infestations are rare.

 
Controls: These insects are usually tolerated in the garden. Only under rare occasions are they a major threat to the health of any plant and then should be controlled. Spray in early spring at the first sign of damage with an insecticide like Orthene®, Sevin®, malathion, or diazinon. Once the leaves are rolled, the effectiveness of these insecticides is minimal and a systemic such as Isotox® should be used.
Loopers & Leaf Eating Caterpillars
This heading is inclusive of a very large and broad family of insects. Caterpillars are voracious eaters capable of devouring several times their weight in foliage or flowers as you watch. Typically they cause damage along the edges or margins of leaves or petals. Some will eat from the center of the leaf but damage usually begins along a fold or sharp bend in the leaf. Caterpillars are the larvae of butterflies and moths; therefore, control is not always desired. Know the identity of your pest before controlling them.
Controls: One of the easiest controls to use for any leaf eating caterpillar is BT (Bacillus thuringiensis). This is a bacteria that, when consumed by the caterpillar, causes death while remaining harmless to wildlife and the environment. Hand picking is another viable option as a natural control. This may need to be done at night as some types are nocturnal. Insecticides containing pyrethrins or Orthene® can also be very effective in controlling these undesired pests.
Ants
Ants will find their way into any nook or cranny in your home or garden. They invade your home looking for water during dry periods. They move about the garden carrying a variety of insects from plant to plant as they "farm" them for food. Some take up residence in your fence posts or other wood structure. Believe it or not, ants do provide some benefits in the garden; they are the cleaning crew of the insect world. Is it worth it? You make the call.

 
Controls: A natural control for ants is Diatomaceous Earth; effectiveness: low. Other controls include many of the snail and slug baits, Diazinon, and Orthene®. If controlling ants indoors, be sure that the product is registered for that purpose.

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