Pests
Pest control … what pests are bugging you? Or maybe you don’t know which pest it is but you certainly know what damage it’s creating. Below you will find nine of the most common pests with photos, their descriptions, and the damage to your plants that they leave behind. Have a look … determine your problem and we’ll provide the solution.
Pests
Aphids
Aphids are among the most destructive insect pests on cultivated plants both in greenhouse, gardens and interiorscapes. The damage they do to plants has made them enemies of growers, farmers and gardeners the world over. They also are so damaging due to their abilities to reproduce asexually.

Pest Description

Aphids are small (about 1/8 inch long), pear-shaped, soft-bodied insects that occur in many colors, including black, green, red, pink, yellow, brown, or gray. The best characteristic for identifying aphids is the two cornicles (tail pipes) found on the rear of their abdomen. The appearance of cornicles can vary with species. As aphids increase in size, they shed their exoskeletons (cast skins). These white cast skins, often mistaken for adult whiteflies or another aphid species, can be found on leaves or stuck in honeydew excretions. Nymphs appear as smaller versions of the wingless adults. Winged adults are similar in color, but slightly darker, primarily a result of their wings.

Aphid Damage

Aphids suck plant sap from leaves and stems through a fine, needle-like stylet. Damage from feeding is quite variable, ranging from no apparent damage to off-color foliage, twisted and curled leaves, gall formation, poor plant growth, and plant dieback. Feeding aphids secrete excess sugars from their abdomen in the form of sticky honeydew. Honeydew supports the growth of black sooty mold which reduces the photosynthetic area of the leaf, which can ultimately result in smaller fruit. In addition, aphids are vectors of several different viruses. Viruses can cause mottling, yellowing, or curling of leaves and stunting of plant growth. In some cases the fruit can be misshapen.

Tips

  • Keeping your garden free of weeds can help to reduce potential aphid hosts. Weeds such as sowthistle and mustard can support large colonies of aphids.
  • Excessive nitrogen can favor aphid reproduction; therefore plants should be grown with appropriate soil fertility levels. Application of less soluble forms of nitrogen, in small portions throughout the season is less likely to promote aphid infestations.
  • Aphids can be physically knocked off of plants with a strong spray of water from a garden hose. In addition, this will also help wash off any honeydew or sooty mold that may be present.
Pests
Caterpillars
Easily found on leaves of plants grown in greenhouse, caterpillars are the larval stage of moths and butterflies. Normally, they are not considered major insect pests of greenhouse crops. However, during summer through fall, adults (moths or butterflies) can enter greenhouses through doors, vents or sidewalls and lay eggs on plants. Caterpillars feed on a variety of plants with their mouthparts, and they can severely damage crops.

Easily found on leaves of plants grown in greenhouse, caterpillars are the larval stage of moths and butterflies. Normally, they are not considered major insect pests of greenhouse crops. However, during summer through fall, adults (moths or butterflies) can enter greenhouses through doors, vents or sidewalls and lay eggs on plants. Caterpillars feed on a variety of plants with their mouthparts, and they can severely damage crops.

Pests
Fungus Gnats
The damp, moist environment in greenhouses favor both fungus gnats and shoreflies. Fungus gnat larvae are translucent, white and legless, about 1/4 inch long when mature and have a shiny black head. The mosquito-like adult is about 1/8 inch long with long legs, a pair of clear wings and long antennae. Fungus gnats are weak fliers and are frequently observed resting on pot media or running over the foliage or other surfaces. The larvae feed on fungi and decaying organic matter and often injure seedlings and plants. Larva feeding occurs on young, tender roots and in the stem at the base of the plant. This feeding injury provides an entry for disease pathogens. A female fungus gnat may lay up to 300 whitish eggs in clusters of 20 or more. The eggs are deposited on the surface or in the crevices of moist soil or potting media. Eggs hatch in about six days. Larvae feed for 12 to 14 days before changing into pupae. The papal stage may last five to six days. Adults live up to ten days. The life cycle from egg to adult requires approximately four weeks depending on greenhouse temperatures.

Pest Description

The damp, moist environment in greenhouses favor both fungus gnats and shoreflies. Fungus gnat larvae are translucent, white and legless, about 1/4 inch long when mature and have a shiny black head. The mosquito-like adult is about 1/8 inch long with long legs, a pair of clear wings and long antennae. Fungus gnats are weak fliers and are frequently observed resting on pot media or running over the foliage or other surfaces. The larvae feed on fungi and decaying organic matter and often injure seedlings and plants. Larva feeding occurs on young, tender roots and in the stem at the base of the plant. This feeding injury provides an entry for disease pathogens. A female fungus gnat may lay up to 300 whitish eggs in clusters of 20 or more. The eggs are deposited on the surface or in the crevices of moist soil or potting media. Eggs hatch in about six days. Larvae feed for 12 to 14 days before changing into pupae. The papal stage may last five to six days. Adults live up to ten days. The life cycle from egg to adult requires approximately four weeks depending on greenhouse temperatures.

Shore flies also occur in greenhouses and are often confused with fungus gnats. The adult shore fly is about 1/8 inch long and has a robust body, very short antennae, shorter legs and dark wings with about five light spots. Larvae are off-white and do not have distinct head capsules. Shore flies do not injure plants through direct feeding, but can carry root rot pathogens from diseased to healthy plants.

Fungus Gnats and Shoreflies Damage:

  • The larvae feed on fungi and decaying organic matter, and often injure seedlings and plants.
  • Larval feed damage can provide an entry point for disease pathogens such as damping-off.

Beneficial Insects and Tips

  • Stratiolaelaps scimitus(formerly Hypoaspis miles) and Gaeolaelaps gillespiei lives and feeds in the soil on both fungus gnat larva and thrip pupae.
  • Dalotia coriaria(Rove Beetles) lives on fungal mates and feeds on shore fly larvae and eggs.
  • Nems beneficial nematodes, kill fungus gnat and shore fly larvae and thrip pupae.

Monitoring Tools:

  • Adult flies can be monitored with yellow sticky cards placed at the base of the plant at the soil line. The cards should be spaced at 1-4 per 93m2(1,000 ft2) in the growing area. Place yellow cards in a horizontal position just above the soil surface or lay them on the top of the pots.
  • Larvae can be monitored using raw potato chunks with the peel removed and placed on the soil surface. Larvae are attracted to the potato chunks under which they move and congregate. Check the potato chunks daily for larvae. Potato disks cut one inch in diameter and 1.3 to 2.5 cm ( 0.5 to 1 in) thick work well. Ten potato disks may be sufficient to monitor a 929 m2(10,000 ft2) greenhouse.

The key to success in controlling fungus gnats is PREVENTION.

Pests
Leaf Miners
Leaf miners are pests which tunnel through the mesophyll of leaves creating distinctive and squiggly patterns. There are several species of leaf miners attack greenhouse ornamental and vegetable crops. Chrysanthemum, gerbera, gypsophila, marigolds and asters are common ornamentals which leaf miners attack. In Ontario, however, vegetable crops, such as tomato and cucumber, are less commonly attacked. Leaf miner damage is unsightly and, if left untreated, can end up causing serious damage to a plant.

Pest Description

Leaf miner adults are small (2-3mm), shiny, black-and-yellow flies that lay eggs into leaves. The hatched larvae feed between the leaf surfaces mining through the leaves. The larvae are small, pale and yellow maggots. If the leaf is held up to the light or if they are dissected out of the mine, they can be seen clearly. When mature, they cut a hole in the mine and emerge from the leaf. Mating, egg-laying, larval emergence from leaves and adult emergence from pupae tend to occur in the morning, depending on temperature and cloud cover. Leaf miners can be complete their life cycle within 14 days at temperatures of 300C, and up to 24 days at 200C. In summer, they develop faster than usual. Most of their immature life cycle is spent in the pupal stage, which can take more than a week. When temperatures are cool, pupae can survive up to 90 days.

Leaf minder Damage

Found in greenhouses, home gardens and landscaped areas, leaf miners feed between the upper and lower surfaces of leaves, but usually the damage they cause is not life-threatening. Damage can result from the egg-laying and the leaf mines. In ornamental plants, even at low levels of damage symptoms, leaf miners reduce the plants’ value. Moreover, high leaf miner population can affect crop quality and make the crop unsaleable since the mines can reduce the photosynthesis ability of plants.

Tips

  • If you see just few sign of tunneling on a leaf, squeeze the leaf at the tunnel between two fingers to crush any larvae.
  • The more healthy the plant, the less chance that leaf miners attack it.
  • It is more effective if you use biocontrol agents on the very first sign of this pest.

Beneficial Insects

Pests
Mealy Bugs
Mealy bugs are common pests that infest a wide range of houseplants and greenhouse plants. Mealy bugs weaken plants and excrete a sticky substance (honeydew) on foliage, which allows the growth of sooty moulds.

Pest Description Mealy bugs are small insects approximately 1-4 millimeters long and oval in shape. The females are covered with a white, cottony or mealy wax secretion and look like tiny cotton balls on plants. This reduces the plant’s aesthetic value. Some mealy bug species have filaments or “tails†around the edge of the body. Immature males and females look similar, but they’re very different as adults: The adult male looks like a gnat with one pair of wings. (Only the adult males fly.) Female crawlers (mobile stage) go though four developmental stages until they reach maturity.

Mealy bug Damage: Once the crawler selects a feeding site, it inserts its mouthpart (called a stylet) and begins feeding on plant sap. Plants are damaged by:

  • A sticky waste substance which is excreted by the mealybug. This waste substance is called honeydew. This liquid adheres to leaves and provides a medium for sooty mold to colonize and grow. Sooty mold is black and eventually covers leaves and stems. This mold stops infected portions of the plant from photosynthesizing and causes aesthetic damage.
  • In addition to the sooty mold, plant damage is caused by the mealy bugs sucking plant sap and the pests’ toxic saliva, both resulting in distorted plant growth and premature leaf drop. Plant leaves also develop yellow spots.

Beneficial Insects:

  • Chrysoperla spp., Green lacewing larvae feed on the crawler stage of almost any mealy bug.
  • Micromus variegatus, Brown lacewing aggressively consuming any of the sucking insects such as mealy bug They appear to find prey by smell.
  • Cryptolaemus montrouzieriMealy bug destroyer, is a ladybug that feed on most mealy bug species (although it doesn’t do well on the longtail mealy bug).

Tips:

  • Horticultural Soaps work well in controlling this pest. The tricky part is mealybugs tend to hide very well where leaves attach to the stem, so make sure you get coverage there. Horticultural soaps don’t have systemic properties, which means when spraying, the product must come in contact with the pest.

A word of warning: You can burn leaves with horticultural soaps. These products need to be applied when the air temperature is cool. Make sure your plants were watered well the day before you apply your control – never spray wilted plants. Following labeled rates also reduces the risk of leaf damage. Also, make sure beneficial insects are not present when you spray

Pests
Scale
As a sap-sucking parasitic pest, scale is common on backyard trees, ornamental shrubs, greenhouse plants and houseplants. They have odd shape and resemble shell-like bumps rather than insects. Heavy infestations build up unnoticed and may result in poor growth, yellowed leaves of the plants.

Pest Description

Scales are small and have oval and flat body with a protective brown shell-like covering. They vary greatly in colour, shape and size. Different varieties of scale can be white, black, orange, or colours that blend in with the plant’s colour, making them harder to detect.

Scale insects can be divided into two groups:

Armored (Hard) – Secrete a hard and protective covering (1/8 inch long) over themselves. The armored scale lives and feeds under this spherical armor. Armored scales don’t have mouthparts, and they do not secrete honeydew. Male scales are smaller and more elongated than female ones. Female armored scales keep their eggs under their scale coverings for protection until they hatch. Freshly hatched scales are only about the size of pinhead. Once a location is selected, females attach themselves to a plant, losing their legs in the first molting. While females are immobile, males can move on the plant.

Soft – Secrete a waxy film (up to 0.5 inch long) that is part of the body. They may not come from as large a family as armored scales, they are larger in size. Females have elongated shape. In most cases, they are able to move short distances and produce a large amount of honeydew while they are feeding. Soft scales more vary in shape from flat to almost spherical than armored ones do.

Scale Damage

Generally, they target the undersides of leaves and around leaf joints. The honeydew from scales promotes a black mold (known commonly as sooty mold) that colonizes and grows on the leaf surface. Sooty mold eventually covers leaves and stems. Also, it inhibits infected parts of the plant from photosynthesizing as well as causes aesthetic damage. Ants are often present as well to feed on the sugary honeydew.

Scale-damaged plants look withered and sickly. Leaves turn yellow due to the insufficient photosynthesis activity and may drop from the plant. Heavily infested plants produce little new growth. If scales are not controlled, death of infested plants is possible. Once a plant is dead, the scales move to find a new host, and the damage is repeated on the new plant.

Tips

  • Dispose of infested branches, twigs and leaves to get rid of scale insects.
  • The newly hatched level can be controlled effectively most.
  • For indoor plants, try to remove scale by rubbing gently with a sponge dipped in rubbing alcohol. The alcohol should kill the scale, but the dead insects will remain on the plants.
Pests
Spider Mites
As often found on the undersides of plant leaves, spider mites, also called “webspinning mites”, are common North America, and they attack both indoor and outdoor plants. They are most common in hot, dry conditions, especially where their natural enemies have been killed off by insecticide use.

Pest Description Spider mites have 4 pairs of legs, so they are not true insects, but arachnid, relatives of spiders. Adults are reddish brown or pale in colour, oval-shaped without wings and very small 0.4-0.6 mm long (around 1/50 inch long)- about the size of the period at the end of the sentence. To the naked eye, they look like tiny moving dots.

A female lays six eggs a day, and over lifetime, it lays 100 or more eggs on the undersurface of foliage. Spider mite eggs are spherical and translucent becoming cream coloured before hatching. Young spider mites called larvae resemble their parents except they are way smaller and have only 3 pairs of legs.

The most common spider mite speices is two-spotted spider mite, Tetranychus urticae Koch. This mite is oval in shape, about 1/50 inch long and may be brown or orange-red, but a green, greenish-yellow or an almost translucent color is the most common. Overwintering females are orange to orange-red. The body contents (large dark spots) are often visible through the transparent body wall. Since the spots are accumulation of body wastes, newly molted mites may lack the spots.

Spider Mite Damage Spider mites have a host range of hundreds of plant species, including all major vegetable crops and many ornamental crops. Each spider mites suck plant fluid from foliage, and large infestations cause visible damage. At first, leaves show patterns of tiny spots. As feeding continues, the leaves turn yellowish or reddish and drop off. The mite activity is visible in the tight webs that are formed under leaves, twigs, and fruit. Damage is usually worse when compounded by water stress.

Tips

  • Spider mites are often difficult to see with the naked eye, but their presence on infested host plants can be detected by holding a white sheet of paper under a branch and tapping the branch against the paper. If mites are present, they will show up on the paper as tiny moving dots.
Pests
Thrips
Thrips are important greenhouse pests. They have a wide host range consisting of hundreds of plant species that includes all the major greenhouse vegetable crops and many commonly grown ornamentals. Thrips are very small in size (1-3 mm) and live cryptically such as in the flower bud, new leaves or growing points of plants. This pest has readily developed resistance to pesticides and there are few or no effective pesticides to control them.

Pest Description

Thrips are tiny, slender insects with fringed wings. Depending on the species, they are about 1-3 mm in length when fully developed. Adults vary in colour from greyish, dark brown or black through to yellow or straw brown. Immature thrips are usually white or yellow with red eyes.

The most common species found in greenhouses is western flower thrips (WFT), Frankliniella occidentalis which can cause damage by direct feeding (silvery appearance on leave surface) and can cause the transmission of plant viruses. WFT are 1.5 to 2 mm in length (females larges than males). The bodies are yellowish brown in colour and they appear to have a dark strip on the top surface of the back. The eyes are red. The larvae are white (early instars) and become yellow as they age. WFT feeds on almost any flowering plants including carnations, chrysanthemums, gerberas, geraniums, marigolds, pansies, and roses are the major host plants.

Onion thrips adults are smaller in size (1.2 to1.3 mm) and are a fairly uniform yellowish brown colour. Their eyes are grey and they have grayish antennae. These Thrips resemble WFT and are difficult to distinguish. They feed on a wide variety of vegetable plants, small grains, field crops and weeds.

Echinothrips adults are larger thrips (1.6 mm) and are very dark brown in colour. The wings are also dark with white band across the shoulders. They feed on many ornamentals and It has been found on poinsettias, cucumbers, and peppers.

Chilli thrips adults are smaller (adults up to 1.2 mm) and pale yellow to almost white in colour. This thrips feed on more than 100 plants from about 40 different families which include vegetable, fruit and ornamentals.

Damage

Thrips feed with piercing/sucking mouthparts resulting in the removal of cell contents, leaving white/silvery feeding scars on leaves or translucent spots and streaking on flower petals. Feeding is also characterized by tiny, black, fecal deposits on leaf surfaces.

Thrips can also vector (transmit) a family of viruses known as tospoviruses, the most important of which are impatiens necrotic spot virus (INSV) and tomato spotted wilt virus (TSWV). Tospoviruses have a host range of hundreds of plant species and cause a wide variety of symptoms including stunting, stem and leaf necrosis, distortion, chlorotic and nerotic leaf lesions and concentric ring spots and line patterns.

Beneficial Insects and Tips

Soil Stage Controls

  • Stratiolaelaps scimitusand Gaeolaelaps gillespiei: target a variety of prey such as thrips pupae, fungus gnat and shorefly larvae and springtails in soil.
  • Dalotia coriaria: is a predatory rove beetle that feeds on pests in the soil.
  • Steinernema feltiae: feltiae is most commonly recommended for control of fungus gnats (sciarid flies), thrips and leafminer.

Foliage Stage Controls

  • Orius insidiosus: is a generalist predator, feeding on various soft-bodied insects and mites, but thrips are its preferred food source. Both the adults and immature stages of Orius are predatory.
  • Amblyseius swirskii: swirskii feeds on thrips, whiteflies (greenhouse whitefly and Bemisia), and spider mites. It is known to perform better when fed on a mixed diet of both whitefly and thrips. It also feeds on pollen and can establish on crops in the absence of pests if there is a pollen source available.
  • Neoseiulus cucumerisis a predatory mite, previously known as Amblyseius cucumeris. Because  cucumeris feeds only on the first larval stage, it can take 4-6 weeks for control to be evident, longer if thrips were well-established before N. cucumeris was introduced. N. cucumeris can harass older Thrips which can result in better control1.
    • 1Neoseiulus cucumeris reduced feeding activity of 2nd instar western flower thrips by 22%. Jandricic, S.E. et all, (2016). Non-consumptive predator effects on a primary greenhouse pest: Predatory mite harassment reduces western flower thrips abundance and plant damage. Biological Control, Volume 95, 5-12.
Pests
Whiteflies
Whiteflies are a major pest of greenhouse crops, including tomatoes and cucumbers as well as many ornamental species, such as poinsettia, gerbera and a number of spring crops. Many weed species are also hosts of whiteflies and often serve as sources of infestations.

Pest Description

Common in crops, whiteflies are tiny (approximately 1/16 to 1/10 inch) with powdery white wings and short antenna. Their wings are various depending species; wings which have a dark zigzag pattern (Banded winged Whitefly), wings which have triangular shape (Greenhouse Whitefly), or wings which have oval shape (Sweet potato Whitefly).

Their eggs are yellow or gray with the size of a pinpoint, and their larvae are flattened round in shape without legs, translucent, and 1/30 inch in size.

Whitefly Damage

They are often found in thick crowds on the undersides of leaves, and they feed on plant sap from new growth causing stunted growth, leaf yellowing and reduced yields. Since, like aphids, whiteflies secrete honeydew, leaves maybe sticky or covered with a black sooty mold.

The worse fact is that whiteflies are vectors that transmit over a hundred different plant viruses which can significantly damage to crops. When the whitefly moves to a new plant and starts feeding, viral particles enter the plant and start an infection cycle. Depending with plant species, both the symptoms they show and their susceptibility are various.

Tips

  • Removing weeds from around and within the greenhouse can make it difficult for whiteflies to reproduce as well as cycle between greenhouse crops and the surrounding environment.
  • Avoiding or removing plants that repeatedly host high populations of whiteflies is also helpful to reduce the population.
Pests
Grubs
Lawn Grubs, often called White Grubs, are the immature form of different Scarab Beetles, such as Japanese Beetles, June “bugs” (beetles) or the European Chafers. These white, C-shaped creatures have soft bodies with legs near the head.

Description

Lawn Grubs, often called White Grubs, are the immature form of different Scarab Beetles, such as Japanese Beetles, June “bugs” (beetles) or the European Chafers. These white, C-shaped creatures have soft bodies with legs near the head.

Damage

Are skunks or raccoons digging up your lawn? Do you have large patches of dead grass? These are signs you have lawn grubs.

Grubs feed on grass roots (and organic matter in the soil), causing sections of grass in the lawn to die. Grubs eventually turn into adult Beetles and emerge from soil to mate and lay eggs.

Tips

In the spring (May) when soil temperature is 10C (50F) or warmer and grubs are seen in the soil. An application will stop grubs from damaging your grass roots. Apply in autumn (end of August to September) eliminating grubs thus preventing fall and following springs damage. Next years application should be in the fall.

100% Safe for people, pets, plants and even earthworms.

The lower mainland In BC is considered a microclimate so if applying nematodes for chafer beetle in this area, the optimal application time is mid July to mid August. This is when the eggs have just hatched and the grubs are at their most vulnerable.

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