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  • W. H. Perron

Organic gardening to limit pests

Updated: Jan 16, 2020

Pests are often attracted to unhealthy plants that can be caused by non-compliance with basic rules such as lack or excess of fertilizer, compost or manure not enough decompose, insufficient or excessive watering, no or bad rotation of crops, ...


Anthocyanus of Raspberry (Anthonomus rubi)

Despite its name it attacks the flower buds of raspberry, strawberry, bramble and rose. The damage presented by this insect is rarely important, but in case of strong attacks deal with the insecticide containing pyrethrum.

The adult is a small weevil measuring 2 to 4mm long, matte black. It has a long mouthpiece (rostrum), slender antennae inserted on its rostrum. It feeds on young leaves and petals of roses. They spend the winter diapause under the bark or various shelters. In the following spring he mates. The female will introduce an egg by drilling with her rostrum directly into the still green flower bud. The egg hatches, the larva feeds and pupates in the flower bud, and the adult then comes out piercing the flower bud. The damage is characteristic: the attacked flower buds do not develop, dry out and eventually fall. Despite its name it attacks the flower buds of raspberry, strawberry, bramble and rose.


Cabbage maggot - Hylemya brassica Attacks the cabbage family, celery and beets. The larva digs through or eats the root surface leaving brownish furrows. The plants become stunted, the lower leaves fade, fade more often in the sun and also die more often. May introduce bacterial and fungal diseases such as soft rot, blackleg.

Harmful stage: larvae

Adult (O.6 cm) looks like a little fly; it begins to emerge in April.

Eggs are small and white hatched in 3 to 7 days.

Adult lays in the soil or at the base of the plants.

Larvae (0.6 cm): White tip, without legs; rounded at the back and pointed at the front; becomes pupa after 3 to 4 weeks.

Pupa (0.6 cm) is found in the soil between 3-15 cm deep; the adult emerges after 2 or 3 weeks or hibernates in the soil.

Generations: 2 to 4 per year

Organic gardening solutions:

  • Place tin cans, filled with hardwood ash, in the soil around the stems

  • Add a good amount of hardwood ash near radishes

  • Arrange oak leaf mulch or tarred paper at the base of the stems when transplanting seedlings

  • Cover layers with cheesecloth to prevent adults from laying around plants

  • Use radishes as bait and remove roots before the cycle of the insect is completed

  • Rotate with non-susceptible crops (legumes, grains) and wait 3 years between cabbage plantations

  • Apply diatomaceous earth to the roots during transplantation

  • Speck in mid-June because the plants are less sensitive


Cabbage weevil (Ceuthorrhynchus pleurostigma)

It can also attack beet or radish. The damage presented by this insect is rarely important, but in case of strong attacks deal with the insecticide containing pyrethrum. The eggs are deposited in the petioles and the larvae migrate more or less quickly to the marrow of the plants that can support these hosts without damage.


Cabbage worm / cabbage butterfly - Pieris rapae Attacks the cabbage family, lettuce and nasturtiums. Made big holes in the leaves; digs into the heads later in the season, leaving behind green droppings.

Harmful stage: larvae

Adult (5 cm wingspan) is a white butterfly having 3-4 black spots on each wing. It lays separately upside down leaves of small round.

Egg yellow: It hatched in 7 days or more. T

Larva (4 cm) is a green caterpillar, velvety with orange bands on the back and yellow, broken on the sides; feeds for 15 days then becomes chrysalis.

His cocoon held by a thread on the leaves, stems or other objects. The adult emerges in 10 days. Generations: 2 to 3 per year hibernates as a pupa in plant debris. Organic gardening solutions:

  • Pick up by hand;

  • Sprinkle wet plants early in the morning with wood ash, salt (1 teaspoon in 2 liters of water), rye flour, safe milk or an infusion of garlic;

  • Spray diatomaceous earth or Bacillus thuringiensis

  • Pick up all the debris in the garden.


Codling moth (Laspeyresia pomonella), plum tree (Grapholta funebrana)

The codling moth is a small butterfly 14 to 22 mm in size of the family Tortricidae. The adult insect has a greyish appearance. The fore wings are gray with brown ribbons, and at their extremities a large brown spot streaked with three fine golden lines. The hindwings are totally brown gray.

The codling moth winters as a larva in a cocoon, under the bark of trees or on the ground. From April to June, first generation adults appear. Spawning is about 5 days after mating, when the temperature exceeds 15 ° C with an air humidity of more than 60%. The larva first knows a so-called walkman stage. She enters a fruit she leaves at the end of her development to weave a cocoon into a shelter. The damage can be significant. One of the characteristics is the fall of the fruits because the larva develops in the fruit then migrates to the pips. Then either she pupates and gives a second-generation butterfly, or she enters diapause.

Organic gardening solutions:

  • Glue strip on the trunk

  • Pheromone trap


Colorado potato beetle - Leptinotarsa decemlineata Attack the potato, tomato, eggplant and several weeds. Quickly spread the plant and leave a black deposit on the leaves while eating. Transmitter of diseases such as tuber spindle, bacterial wilt.

Harmful stage: larvae and adults.

Adult (1 cm) is corpulent, oval; 10 yellow stripes and 10 black stripes on his convex back.

The eggs are yellow; laid in clusters (12 or more) under the tips of the leaves, is found for a period of 4 to 5 weeks; hatched in 4 to 9 days. The larva (1.3 cm) is red and arched with 2 rows of black dots on each side of the abdomen; head our; matures in 2 to 3 weeks. Go to the soil and the adult emerges after 5 to 10 days.

Generations: In our gardens we can have from 1 to 4 generations, the adult hibernates in the soil at 20-25 cm from the surface.

Organic gardening solutions:

  • Pick up by hand;

  • Grow resistant varieties

  • Plant between the rows garlic, marigolds, nettle and beans;

  • Plant wild horseradish (in containers, to prevent rows;

  • Make a mulch with 30 cm of hay or straw;

  • Spray with "bug juice" (mix larvae and adults of Colorado potato beetle, water and liquid soap); Sprinkle with diatomaceous earth Spread rotenone as a last resort.


Cutworm - Noctuidae (several species)

The larvae attack the cabbage family, corn, tomato, beans, pepper, squash, etc. It cuts the stem of the plants near the ground; some species climb and eat the leaves. Damage is especially important during seedling emergence, planting and transplantation.

Harmful stage: larvae

Adult (up to 5cm wingspan): Butterfly with dark gray wings with various markings. Eggs are laid singly or in groups on stems and leaf sheaths.

Larva (2-5 cm) is plump, having a soft body and dull colour, some have rough skin; feeds at night and hides the base of the plants near the soil surface (3 cm) during the day; curls up when disturbed can hibernate in the ground or under debris, etc. (Most species are only one generation old).

Pupa: In the soil, emerges after 1-8 weeks or after winter (multi-generational species). Generations: 1 to 2 per year, most hibernate as larvae.

Organic gardening solutions: • Place a cane, plastic cup, cardboard neck or sheet of metal around the plant stem during transplantation; allow the collar to protrude at least 5 cm from the ground surface and drive it at least 3 cm below the ground • Put a toothpick or a stick against the stem of the plants (this practice disturbs their habit of cutting) • Bunch around seedlings early in the season to expose worms • Pick up at night with a flashlight, on the ground surface or on the plants; • Apply diatomaceous earth or Bacillus thuringiensis to the soil around the seedlings • Plowing autumn • Remove weeds and crops at the end of the summer do not put it in the compost • Spread crushed egg shells, limestone, ash, agricultural sulphur at the base of the plants • Make bait with bran, molasses and beer • Place a mulch of oak leaves around the seedlings


Eastern tent caterpillar - Malacosoma americanus

The caterpillar attacks the leaves of wild cherry trees, wild plum trees, apple trees and other trees in the orchard. Weakens but rarely kills trees. Populations fluctuate greatly; their cycles usually vary between 7 and 10 years depending on the natural controls.

Harmful stage: larvae

Adult (4.5 cm wingspan): Butterfly yellowish-brown to dark chocolate-brown (paler female), with two white and oblique stripes on the wings. Egg: Inside a sheath or sheath dark brown 2 cm long (150 to 350 eggs) surrounding the branches of susceptible trees; laid in autumn.

Larvae (5 cm): Black caterpillar with whitish stripes on the back and blue, young and red-brown markings; sparse hairs; make a common canvas in the forks of trees; mature in 4 to 6 weeks.

Pupa: In a hard, yellow-white cocoon on tree trunks, fences, debris and on the ground. A butterfly comes out after 2 weeks.

Generation: 1 the egg hibernate

Organic gardening solutions: • Remove the new canvases spun in the trees, in the spring, by wiping them with a cloth soaked in kerosene (not lit!) • Destroy cases and cocoons in the fall or winter (not to be confused with tapered cocoons of the praying mantis as it is a beneficial insect) • Spray the caterpillars with Bacillus thuringiensis • Use light traps (electrical insecticide) to catch adults; • Sprinkle with diatomaceous earth.


European corn borer - Ostrinia Nubilalis

Attack corn, pepper, eggplant, beetroot, beans, potatoes, tomatoes, oats, soy beans, various flowers such as chrysanthemum, dahlia, gladiolus and some weeds. The larva digs holes in the stems and leaves fine sawdust all around. It breaks the stems and bristles and also attacks the ears and leaves. Several larvae can infest a plant.

Harmful stage: Larvae

Adult (2-5 cm wingspan): Buff-coloured butterfly with wavy bands across the wings (smaller and darker male); appears from May to August; night.

Egg: White to yellow; flattened mass (5 to 50), upside down leaves; hatched in 7 days.

Larva (3 cm): flesh-coloured caterpillar with little brown spots and a head; hibernates in the plant tissues (e.g. in the base of the plant near the ground) and pups there in the spring.

Pupa: In spring, loses its cocoon in the cavity where the larva has hibernated.

Generations: 1 to 2 per year.

Organic gardening solutions:

• Plant resistance varieties

• Rotate with legumes, for example

• Flip the stems into the ground in the fall or shred them and bury them in early spring

• Collect by hand by slitting the stem under the hole made by the larva (using the nails) and remove it

• Use light traps (electric insecticide) to capture adults

• Apply Bacillus thuringiensis

• Plant later

• Use a parasite such as the tachinid fly (Lydella thompsoni).


European earwig - European earwig - Dermaptera Generally beneficial because it eats organic debris, insect larvae, snails, etc.But it occasionally infests flowers (dahlias, carnations, chrysanthemums, carnations) and vegetables (lettuce, celery, potato, beet, bean , strawberry). Nymphs eat seedlings and make holes in the leaves of flowers and vegetables; adults eat the stamens, the base of the flower petals and the ripe fruits of the orchard.

Harmful stages: adults, nymphs

Adult (1.5 cm) is dark brown, thin, elongated; pair of clips at the back; runs more often than he steals; he curls his abdomen and gives off an odour when he is disturbed; looks a bit like beneficial Staphylinids that do not have forceps.

Eggs are white, about 30 are laid in underground nests and incubated by the female, they hatch in April.

The nymphs are kept by the female, at a young age. They develop gradually and become adults in July. Generations: 1 to 2 per year, they hibernate as adults or as eggs.

Preventive measures: • Remove grass clippings; • Remove all hiding places (where it is black, wet and cool); • Grow as early as possible in the spring to expose the eggs to the surface for destruction; • Exposing adults to the surface to attract predators (birds); • Start your vegetable garden as soon as possible.

Organic gardening solutions: • Place diatomaceous earth in hiding places such as cracks and crevices, around and on wooden piles, around the foundations and garage, in the tubular legs of the lawn furniture, around and in the dog kennel. do not water the grass after applying diatomaceous earth and do not apply it during a windy day. • Water earwigs directly with diluted dish washing liquid when viewed alone or together; Do not water your lawn with pesticides to suppress the insects because you will kill all the beneficial insects, causing an ecological imbalance on your ground; • Arrange traps made of rolled newspapers, bamboo tubes, rolls of cardboard toilet paper and fill them with peanut butter, fish oil, vegetable oil or diatomaceous earth; every morning, gently tap the traps to dislodge the earwigs and drop them in soapy water to destroy them. • Place other traps made of corn oil, fish oil with water or vinegar (half: half) in a small, buried can, leaving the end of the pile out of the ground. • Both kinds of traps can be put in the garden among flowers and vegetables; also place them under trees and shrubs and near hiding places. • Put a seal of soapy water in the garden where they will climb and drown. • Place two fluted boards on their sides, groove groove. • Put small flower pots filled with straw and upside down on a peg. • Use "bug juice": mix earwigs with water in a blender and water other earwigs with this preparation


Flea beetle - Epitrix cucumeris Attack potatoes, eggplant, tomatoes, peppers, etc. The adult makes small holes by eating the undersides of the leaves, which sometimes become young and die. The larvae attack the underground parts transmitting plant diseases (tuber spindle, anthracnose, rot, scab and smallpox tubers).

Harmful stages: larvae and adults

Adults (1mm) Brown or black, jump when disturbed; feeds on weeds and tree leaves until the exit of vegetable shoots; may be harmful for more than 2 months; hibernates in the soil under crop debris. The eggs are tiny, hard to see, laid in June on or in the soil near the base of the plants; hatched in 7-10 days.

The larva (1cm) is thin and white, its head is brownish, it eats the roots and the tubercles of the plants during 2 to 4 weeks.

Its pupa is in the soil during in 7-10 days.

Generation: 1 to 4 per year.

Organic gardening solutions: • Rout frequently to kill eggs and return the soil after harvest to kill adults • Remove weeds and plant debris as these their hibernation sites • Repel them with small amounts of soot and agricultural lime (1: 1) • Sprinkle the plants with ash 2 to 3 times a week, at morning dew • Protect seeds with gauze; sow a lot of seeds and clear up after the dangers of spring attack are over • Apply a solution of garlic or diatomaceous earth • Place a sticky screen or boxes around infested plants to capture flea beetles when they jump • Between the rows, plant vegetables of the cabbage family (Brassicaceae) • Plant near plants that give tise of the potato does not like shade); as a last resort, sprinkle with rotenone


Mites (colourless-green-yellow-red)

40 species of plant can be attacked by mites, in the gardens it is mainly the yellow mites that you will find (Tetranychus urticae) and in arboriculture the red mite (Panonychus ulmi). The mite mainly develops when it hot and on plants with an excess of nitrogen. By sucking the sap, it causes yellowing of the leaves. Difficult to see by their small sizes can be identified by the presence of a thin spider web and mainly after watering the foliage.

Organic gardening solutions: • Regularly water the foliage of the plants with water • Treat with nettle fermentation manure • Treat with pyrethrum insecticide • Treat trees with mineral oil in winter (destruction of eggs)


Spinach leaf miner - Pegomya hyoscyami Attacks spinach, beetroot, sugar beet, lettuce, carrot, parsnip, celery, butt and several weeds such as lamb's-quarters, black nightshade and stellate-medium. Feeds between, and not through, the surface of the leaves. The dug tunnels are at first narrow and winding; then widen, as the larva grows, to form white spots filled with dark excrement; can reach the tunnels of other larvae. Larvae can delay the growth of plants. The leaf miner is favoured by a cool and humid temperature. The first generation does most of the damage.

Harmful stage: Larvae

Adult (6 mm): Thin, gray fly with black hair; begins to emerge in April or May.

Eggs (0.8 mm): White, oval, carved; 2 to 20 laid in mass below the leaves; hatched after 3 to 5 days; the female lays about 300 eggs in a month or more.

Larva (nearly 8 mm): Pale-to-whitish-green tip with a pointed head (other groups of leaf miners have dark heads in a capsule); eats the tissue between the leaf surfaces; can go from one sheet to another. When the larva has reached its full size (1-3 weeks), it falls to the ground to become pupae.

Pupa: Usually found in the first 5-6 cm of the soil; sometimes in the waste on the ground; rarely in tunnels dug by the leaf miner in the leaves. The adult emerges after 2-4 weeks or (if it is the last generation) after the winter.

Generations: 2 to 4 per year

Organic gardening solutions: • Collect damaged leaves and burn or compost them; usually, the plant relies on it; • Destroy crop residues and susceptible weeds around; • Returning the land in the spring can be beneficial; • Spinach grown late in the season can escape damage; • Larvae are very susceptible to parasitic wasps (these usually control the 2nd to 4th generation and are favoured if some flowers are present in and around the garden such as parsley, dill and wild carrot. • A heavy summer rain can wash eggs and kill pupae; violent watering can have the same effect.


Slug - Limacidae (Mollusca) Attacks the cabbage family, lettuce, potatoes, flowers, berries, etc. The slug is active at night; she eats the leaves leaving a viscous trail (shiny when dry); feeds on roots in winter.

Harmful stage: Adults

Adults or immature (up to 20 cm): Viscous, soft body without paw; looks like the snail without shell; can live more than a year; hides in sheltered and humid places during the day.

Eggs are laid in mass in damp places and held together by a sticky substance; hatched in 1 month.

Organic gardening solutions: • Dispose of shelters by leaving no piles of plant or weed rub in the garden. • Regularly remove slugs hiding under boards, lettuce leaves touching the ground, etc. or pick them up at night with a flashlight. • Sprinkle diatomaceous earth on leaves and resting areas. • Apply wood ash or fine sand to the soil around the plants and the garden (irritates their bodies). • Place stale beer in plates slightly buried in the ground or canned food at ground level on the edge of the garden; they will be attracted and drown. Empty each morning and repeat. • Protect toads that swallow them; surround the garden with a barrier made of chicken brooch. • fine mesh; press it 5 cm into the ground and let it protrude 15 cm above the ground by bending 5 cm from the top to the outside.


Taupin Wireworm / Click beetle - Elateridae

Very harmful and difficult to control; Attacks corn, potatoes, beets, beans, lettuce, cabbage, carrots, onions, peas, turnips, grains and herbs. Eats underground parts, stems, roots and seeds. The plants do not germinate or carry sparse and then die or wither in the season.

Harmful stage: larvae

Adult (1.5-2 cm) a long brown or black beetle that makes a flying sound; he turns around when he is placed on his back. He lives 10-12 months on or under the ground, but he can fly. Do not confuse with beneficial beetles.

Egg laid alone in moist soil in May-June; hatched in a few days or weeks.

The larva (3.5 cm) is hard, shiny, articulate, thin, yellowish to brown; is found all year in most soils, lives from 2 to 5 years, moving only a few meters during this period; can sting when seized in the hand.

Pupa is found in the soil at the end of summer and the adult emerges the same autumn.

Organic gardening solutions: • Avoid planting susceptible crops if the garden is located in a location where grass has previously grown. • If turf is incorporated into the soil, it should ideally be cut, stacked, composted and returned to the soil only when it is well decomposed. • Rotate crops. • Return the first 25 cm of soil very early in the spring, leaving it for a few weeks. • Make baits with pieces of potatoes by placing the cut face down, 5-10 cm deep, then watch; or perforate the potatoes and impale them on batons, then bury them to 2 or 3 cm deep; shake the worms regularly in soapy water. • Collect under boards resting on the ground surface.


Tomato Sphinx - Tomato hornworm - Manduca quinquemaculata Attacks tomato, chili, potato, eggplant and tobacco. Eat the fruits but especially the leaves.

Harmful stage: larvae

Adult (12 cm wingspan): Moth, greyish brown; siphon the nectar; come out of his chrysalis in the late spring.

Egg: Round, greenish; laid separately on the underside of the leaves.

Larva (10 cm): Green with white slashes and a "horn" at the back of the abdomen; may look like a rolled sheet; identified by the dark green droppings she leaves on the ground below the plant; feeds voraciously for 3 to 4 weeks and then becomes chrysalis.

Pupa (7 cm): Dark brown, hard and spindle-shaped; stands 10 to 12 cm in the ground; hibernates as a pupa.

Generations: 1 to 4 per year.

Organic gardening solutions:

• Pick up by hand and put in soapy water unless it is covered with white cocoons (indicates the presence of the braconid parasite-an effective means of natural control). • Remove crop residues immediately after harvest (reduces hibernating populations). • Spray young larvae of Bacillus thuringiensis1 (or rotenone, as a last resort). • Trapping adults with light traps (electrical insecticide). • Repel with marigold, borage and parsley as companion plants.


White fly White flies can affect many plant species, indoors and outdoors. They have a small preference for tomatoes, melons, cabbages, but also for fuchsia, azalea, and other vegetable or ornamental plants. They weaken the plant by sucking the sap and its honeydew allows the development of sooty mold.

There are several species of white fly but coming from South America, they all like the heat. Three are particularly to be feared: • The greenhouse white fly (Trialeurode vaporarium): it can be found in greenhouses, sashes or in the interior of houses • The white fly tobacco (Bemisia tabaci): can infest many plants but rather warm • The cabbage white fly (Aleyrodes proletella): It is found mainly in vegetable or ornamental gardens

Organic gardening solutions

• Keep the soil moist. • Ventilate the greenhouses and frames to lower the temperature. • Yellow traps (under glass). • Treat with black soap. • Treat with pyrethrum insecticide.


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