Insecta Coleoptera

garden-weevils

Above image courtesy of © State of Western Australia (Department of Primary Industries and Regional Development, WA

What are Garden Weevils and How to Get Rid of them

The Garden Weevil (Phlyctinus callosus), also known as the Banded Fruit Weevil and Vine Snout Beetle, is an introduced insect pest from South Africa. Garden Weevils can cause major damage to the above and below ground parts of edible and non-edible plants. To protect your plants from damage, it’s important to control, prevent and monitor for Garden Weevils.

Description

Garden Weevils are small, typically 7 mm in length.  They have a hardened body that is elongated and oval shaped, in a mottled grey-brown colour, covered in short light-brown hairs.

At the front of the body is the head, with an extended and downward facing snout. At the front and underside of the snout are chewing mouthparts. Further upwards, along the snout, are a pair of short, bent and segmented antennae. Further along are a pair of large, dark-brown, compound eyes.

Behind the head is the first segment (pronotum) of the middle section of the body (thorax).  Attached to the underside of the pronotum is the first pair of legs. The other two pairs of legs are further along on the underside of the thorax. Legs are used for walking and climbing. At the tip of each leg are small hooked claws which help with climbing and gripping.

On the upper side and rear section of the body are two hardened wing cases which are fused and remain closed, rendering Garden Weevils flightless. The rear section (abdomen) is bulbous with a pointed tip. Across the upper and rear abdomen is a prominent, light-brown, horizontal, V-shaped band.

Behaviour

As a defence behaviour, when disturbed, adults will ‘play-dead’ by dropping to the ground and tucking in their legs and antennae and remaining very still.  

Lifecycle

After mating, females lay eggs in batches of 20. Eggs are laid in leaf litter and other debris and also on or near the soil. Eggs are oval shaped and 0.9 mm long. When first laid, eggs are cream-coloured, then age to black.

After 6 - 15 days the eggs hatch, larvae emerge and burrow into the soil. Larvae are 6mm long, cream-coloured, wrinkly and grub-like, with a distinct orange to medium-brown head capsule. Larvae are legless and have chewing mouthparts. Larvae develop in up to 11 larval stages (instars), and cast skins (moult) at each stage.

At the final instar, larvae form a chamber in the soil where they develop into soft and white pupa, aging to whitish-brown and developing 2 large black eyes. After pupating for 1 - 3 weeks, adults emerge in mid-spring and may survive through to winter. Garden Weevils generally have 1 generation per year, however may have 2 if surrounding plants are well irrigated.

Habitat

Garden Weevils feed on various plants such as fruit trees, crops, grasses, shrubs and succulents.

Garden Weevils prefer warm and moist environments.

Garden Weevils are most active during the night and hide throughout the day in areas such as underneath loose bark, in the junction of stems, in bunches of fruit, in curled up leaves, under mulch, leaf litter and other debris. 

Natural enemies

Birds, frogs, reptiles mammals and certain species of nematodes and fungi. 

Best Treatment for Garden Weevils

To control adult Garden Weevils on non-edible plants, as well as broccoli, Brussels Sprouts, cabbages, cauliflower and tomatoes, spray the foliage of plants with Yates Baythroid Advanced Insect Killer for Gardens. This product provides fast-acting and rapid knock-down of Garden Weevils and various other pests in the garden. Spray at the earliest sign of infestation for easy and fast control of population.

Put sticky traps around the trunks of fruit trees and woody vines to help stop Garden Weevils from crawling up and attacking plants.

If larvae are found in the soil, turn the soil over using a garden fork, pick them up and either throw them to the birds; or place them in a plastic bag, seal well, kill inside the bag by squashing, then place into the rubbish bin.

If you have chickens or other fowl, allow them to roam free in the garden.

 

What Plants are Impacted by Garden Weevils

Garden weevils chew holes in young leaves and stems, flowers and flower buds, fruits and roots of plants, such as:

  • Apple
  • Asparagus
  • Berries
  • Carrot
  • Cherries
  • Citrus
  • Grape and Grape Vine
  • Nectarine
  • Parsnip
  • Peach
  • Pear
  • Pelargonium and Geranium
  • Perennial Ryegrass
  • Plum
  • Potato
  • Sorrel
  • Stone fruits
  • Strawberry
  • Succulents such as Crassulas, Cotyledons and Pigface (Carpobrotus sp.)
  • Walnut
  • Various other edible and non-edible plants

Garden Weevils also attack weed species, such as:

  • Capeweed
  • Dandelion
  • Docks
  • Mallows
  • Portulaca
  • Sorrels

Symptoms of Garden Weevil damage

  • Wilting of above-ground parts of the plant, especially leaves, young stems and flowers. This is caused by the chewing of larvae on plant roots, which causes drought stress to plants
  • Reduced plant vigour and growth
  • Stunted root system
  • Irregular rounded holes in leaves, often starting at the leaf edge
  • Notching at the leaf edge
  • Defoliation of young trees
  • Irregular rounded holes in flowers
  • Scarring and lesions to fruit skin and upper layers of fruit tissue
  • Ringbarking of stems which may cause the entire branch full of leaves and/or fruit to die
  • Chewed off stems
  • For the above-ground parts of the plant (leaves, stems, flowers and fruit) sometimes most damage occurs to the lower sections.

How to Prevent Garden Weevils Appearing

Cultural control:

  • Control weeds in the garden such as Capeweed, Dandelion, Docks, Mallows, Portulaca and Sorrels as these plants may act as alternate host plants and harbour Garden Weevils.  
  • Ensure fruit trees are not too close together, to prevent the spread of larvae and adults from one plant to the other.
  • When rotating crops, cultivate and dig over the soil to expose any eggs, larvae or pupae in the soil. This exposes them to predators and helps dry out and kill the early stages of development. If you see any larvae or pupae, dispose of them.
  • To reduce plant pest and diseases and to assist with plant resiliency, improve the soil and ensure plants are well-fertilised and watered. Yates Dynamic Lifter Soil Improver & Plant Fertiliser breathes life back into the soil by adding organic matter, which encourages microbial and earthworm activity. It is approved for use in organic gardens. It is ideal to use all year round on all plants, including natives.

Monitoring:

  • To check for adults, look underneath loose bark, in the junction of stems, in bunches of fruit, curled up leaves, under mulch, leaf litter and other debris.
  • In spring, monitor for adult Garden Weevils and control at the earliest sign of infestation. Small populations are much easier and quicker to control.

Recommended products to control Garden Weevils


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