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Insects & Bugs

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The Garden Doctor on Insects & Bugs INSECT PESTS

How do I know which insects are eating my plants?

Often you find unwanted livestock in the garden - yes, insects and bugs! However, sometimes it's hard to know what the insect is as they hide under leaves and are difficult to see. The Garden Doctor has put together some easy ways to help you identify and control insect problems in the garden. Click Here to see their effective sprays

APHIDS are suckers. They feed by sucking sap out of plants in much the same way as a mosquito sucks blood. Because plants cannot slap the aphids or flick them off with their tail, they just sit there sucking away and multiplying.

Aphids can be a real problem in the garden. Particularly in early spring and autumn. Often Aphids hide in the leaves - so look carefully at your plants when you notice a change in there growth habit. But you don't have to worry there are a number of ways in which you can control them. Look out for insecticides at your local garden store and feel free to ask the advice of the shop assistants when making your purchase.

Symptoms: Stunting, curls, and folds in the leaves. Leaf discoloration; Dieback or "flagging" of newly formed terminals, branch ends, and new leaves; | Early leaf drop; Ring like swellings or knots at nodes and buds Sooty mold and ants frequenting a tree are good indicators of an active or recent aphid attack.


The good news is that aphids are relatively easy to control - just make sure you get thorough spray/dust coverage. Note: like mosquitoes aphids can transmit diseases. Another reason to keep them out of your garden.

Make sure conditions are favorable for sturdy plant growth. Avoid using nitrogen-rich fertilisers. This encourages soft growth which attracts aphids. Inspect plants regularly and squash any aphids that are seen. Pick off heavily infested shoots and leaves and drop into a bucket of soapy water. A strong jet of water from a hose will dislodge aphids. Spray with an insecticide 

CATERPILLARS are chewers and will munch their way through their favourite plants very quickly so spray with Liquid Diazinon or Dust with Derris as soon as possible after you see the first signs of caterpillars.  


small or large holes in fleshy plants
Solution: Inspect plants regularly Spray with an insecticide

  MEALY BUGS  are small flat white bugs that tend to target flax like plants. They are quite mobile and can hide under leaves or behind loose bark so a thorough soaking is important when spraying for these insects.  
Symptom white fluffy spots on plants


Inspect plants regularly Spray with Insecticide Inspect the soil and apply Liquid Diazinon as a drench if they are feeding on the plants roots


CHRYSANTHEMUM MIDGE is a tiny little bug that attacks Chrysanthemums. It is often hard to see as it is so small. What you will probably notice is tiny trails or indentations in the foliage. This is where the Midge has been feeding, and has eaten away the top layer of the leaf.


Spray plant thoroughly with an Insecticide

PEAR SLUG - The Pear Slug is a small slug that attacks the soft juicy leaves of Pear trees. It eats holes in the leaves and is most active in the evening. You will often find the slugs hiding under the leaves during the day.

Solution :

Control with Liquid Diazinon
  SCALE INSECTS are small sucking insects that protect themselves with a scale like cover and live mainly on the underneath of leaves and along young soft stems. Control of Scale is aided by mixing spraying oil with Liquid Diazinon.

The addition of spraying oil helps by suffocating the insect which lifts it's scale coating slightly to try and breathe allowing spray in underneath. Repeat sprays may be necessary to control mature insects. Repeat sprays also increase control of young scale known as "Crawlers", thus breaking the life cycle.


SLUGS AND SNAILS - Snails are chewers, they feed on your precious plants and make unsightly holes in your lovely foliage. They love slightly cool, moist conditions typical of spring Waiting for the first signs of damage is usually too late. Snails can also live and feed in the crowns of trees like Cabbage trees. If you notice holes in the leaves of such trees treat them immediately.


Inspect plants regularly Apply Slug Pellets around effected plants / seedlings when planting
Q. I have slugs and snails in my garden, but am worried about using slug pellets as we have family pets. What can I use that won’t harm our cats and dogs?


Tui Quash Slug and Snail Stoppa kills slugs and snails but is safe for pets and wildlife. Quash is bran-based and the active ingredient is Iron chelate which has a very low toxicity. Quash is the least toxic of all slug and snail bait used world-wide. When Quash is eaten, slugs and snails will feel unwell and go back to their hiding places to die. Shells are seldom found. Quash is kind to the environment. Plants benefit not only from being protected from the ravages of slug and snail damage, but can use the iron released from disintegrating pellets as a valuable nutrient source.

THRIPS are a less known insect although their tell-tale symptoms of silvery leaves especially on Rhododendrons and Photinia are common. Thrips can also do a lot of damage to flower buds. It can be heart-breaking to a keen gardener to watch flower buds of Gerberas or Lisianthus for example open, only to discover unsightly blemishes caused by Thrips. These insects can be controlled by spraying with Liquid Diazinon. Thorough coverage up under leaves where Thrips live is important.

Getting coverage down into flower buds is difficult so a useful trick is to dissolve a small amount of sugar, approximately 1gm per litre of spray, and let stand for an hour or so, before you spray. Overnight is fine if you want to spray in the early morning. Thoroughly spray the infected plants and the Thrips will be attracted out of the buds after the sugar and thus ingest the spray.

Thrips are tiny insects that eat the top layer of the leaves on many plants. Often the plant takes on a silvery appearance when it has been attacked by thrips. Viburnum, Rhododendrons, Azaleas and a number of other shrubs are all very prone to Thrip damage.

No Insects Spraying Oil is suitable for control of thrips on Roses, Fruit Trees, Citrus, Vines and Ornamentals.

WHITEFLY can be a real problem in the home garden. They build up numbers rapidly, especially in warm, sheltered conditions so spraying as soon as possible after the first signs is important. As Whitefly are very mobile and tend to fly off the host plant at the slightest disturbance it is best to spray in the early morning or late evening, when they are less active. Whitefly can have a life cycle as short as three days under ideal conditions so if you are having trouble getting Whitefly under control, spraying three times, three days apart is the best way to break their life cycle.


Q: I have red spider mites on my house plants- how can I get rid of them?


Red spider mite infestation of plants can cause leaves to look unhealthy and dusty or speckled. Heavily infested plants may become covered with fine webs. Leaves may dry up and fall off. Red spider mites like a dry atmosphere so can become a problem during hot, dry summers, especially in house and greenhouse plants.


Apply Tui Mite & Mildew Control (Flowers of Sulphur) by lightly dusting plants. Dust when mites first appear then at 7 day intervals or after rain. Ensure all foliage is well covered. Sprinkle around the surface of pot plants to absorb excess moisture. As red spider mites breed in hot, dry conditions, making the area around infected plants more humid will slow down the breeding rate. Move house plants to humid areas such as bathrooms, or dampen the floor around greenhouse and patio plants. As spider mites love the heat, spray infested plants with iced water (between 0 and 5 degrees Celsius) once or twice a day until they are gone. Isolate invested indoor plants so that they will not infect others Keep plants well watered because water- stressed plants are more susceptible to mites.