Insect and Mite Pests of Raspberries

 
 
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 Aphid | Mite | Crown borers | Fruit worm| Raspberry sawfly | Wasps/hornets/yellow jackets

An important part in the production of any fruit crop is to know what type of insects could cause production losses. A crop is at risk throughout the fruiting cycle. Insects can attack plants during flowering, fruit formation or just before harvest of the plump, juicy berries. A successful pest management program includes: insect identification; pest number and damage monitoring; what population numbers warrant control and knowing when the pest can be effectively controlled.

Aphid


Green Peach Aphids

Identification
  • 1-3 mm long, soft-bodied, pear-shaped
  • main identifying feature--cornicles (tail pipes protruding out of the back end)
  • variety of colors: green, yellow, pink, white, bronze, dark-brown or black
  • adults may be winged or wingless
Life cycle
  • overwinters as eggs on the host plant
  • eggs hatch into "stem" mothers which bear live young; these live young, in turn, bear more live young
  • each mature aphid can produce 50-100 offspring
  • 15-30 generations may be produced per season
  • they can reproduce either sexually or asexually (parthenogenesis - being able to reproduce from eggs which have not been fertilized)
  • males are not produced until fall
  • mating occurs in the fall
  • either an egg is produced; or, another stem mother, which lays the overwintering eggs
Damage
  • symptoms of feeding damage are leaf discoloration, a flattened appearance and ,in severe cases, wilted plants
  • when aphids feed, they puncture plant capillaries; the plant then pumps the sap into the aphid; exudate (excess sap) comes out the back end of the aphid
  • this exudate is called honey dew
  • honey dew makes the leaves and fruit sticky
  • honey dew can also be a nutrition source for the growth of sooty mold fungi (not harmful to the plant, but it can make the fruit unsalable)
  • aphids seldom cause much direct injury, unless present in large numbers
  • they may transmit viral diseases
Monitoring
  • generally, they are found in clusters on the new growth, stems, buds or on the underside of leaves among the veins
  • look for symptoms weekly
  • consider the weather conditions, presence and abundance of natural enemies, and the value and stage of the crop before spraying
Cultural control
  • start with clean stock
  • there are a wide range of natural predators: lady bugs, lace wings, and predatory wasps
Mite



Identification
  • .5 mm, oval, greenish-yellow with 2 irregular dark spots on the back
Life cycle
  • overwinters as an egg, a nymph or an adult on old leaves on the ground or in
  • cracks and crevices of old canes
  • when the plant starts to grow, the mites mate and lay eggs on the leaf underside
  • eggs hatch and begin to feed
  • there can be several generations overlapping
  • hot, dry weather favors population explosions

Damage


Spider mite damage
  • feeds on the leaf underside
  • feeding damage causes yellow spots (mottling or stippling) changing to silver or bronze, then brown with leaf crinkling and curling
  • leaves may dry up and fall prematurely
  • high populations will cause loss of plant vigor
  • feeding on primocanes stunts cane growth, therefore, reducing crop potential for the following season
  • dusty conditions will create a larger mite population, causing more problems
  • injury can be worse after harvest
Monitoring
  • examine for webbing between or under the leaflets
  • webbing indicates a very heavy infestation
  • damage is most noticeable in dry areas of the field
  • diagnostic tools: breathe on leaflets, this causes the mites to scurry about, or tap the leaf over a white sheet of paper to make the pest visible
  • check the canopy top of the fruiting canes
Cultural control
  • spider mite predators become established as plants mature
  • irrigate regularly to avoid water stress on plants
  • eliminate weeds that can be used as alternate hosts
Chemical control
  • begin the chemical control when mites first appear and repeat as necessary
  • ensure leaf undersides are well covered with insecticide
Crown Borers

Identification
  • the adult is a clear-winged moth, 25-30 mm long
  • the abdomen is black with yellow bands and stripes on the thorax
  • new larvae are 3 mm long, whitish with brown heads
  • mature larvae are 25 mm long with white bodies and brown heads
  • larvae have six short legs


    Raspberry crown borer mature larva
Life cycle
  • adults appear in August or September females lay 130-150 eggs on the leaf undersides (2-3 per plant)
  • eggs hatch in September and October, larvae crawl down the cane to the base
  • overwinters in tiny blisters on cane just below soil surface
  • larvae emerge the following spring and feed on primocanes through the summer
  • by October, the larvae are nearly full grown and spend the winter in the feeding burrows
  • they burrow further into the crown to feed the following summer
  • in July, they tunnel and pupate a few centimetres near the outside of the cane
  • it takes 2 years to complete the life cycle
Damage
  • slows cane growth with the possibility of cane death
  • reduced yields
  • new canes are girdled near the ground
  • canes become spindly and are easily broken
  • may also form galls
Monitoring
  • dig the crown out, look for holes and sawdust
Cultural control
  • after harvest, prune out loose canes and ones with galls
  • during the summer, remove and destroy wilting canes

Raspberry canes damaged by crown borer

Fruit Worm

Identification
  • the adult is a small brown beetle, 4 mm
  • the larva is small (6 mm) and whitish-brown
Life cycle
  • adults lay eggs in early spring on or near the developing blossom clusters and green berries
  • larvae feed in the berry and may be in the fruit at harvest
  • mature larvae drop to the ground and pupate
  • overwinters as an adult
Damage
  • presence of yellowish larva on the harvested fruit, making the fruit unsalable
  • adults feed on leaves before they unfold, so leaves have a tattered appearance
Chemical control
  • spray when blossom bud clusters separate and just before blossom opening
Raspberry Sawfly


Sawfly damage

Identification
  • the adult sawfly is 5.5 mm long, black with yellowish-red markings
  • the larva is 12 mm long, light green in color, all body segments, except the head, possess a number of whitish bristles
    Life cycle
  • adults emerge in the spring (blossom time)
  • they lay eggs in the leaf tissue
  • larvae feed during the summer
  • the larvae drop to the ground, construct a cocoon and overwinters as larvae
  • they pupate in the spring
    Damage
    • they feed on leaf underside, flower buds, young fruit and tender bark of growing shoots
    • initial damage appears as small holes in leaves
    • they will completely devour the leaves leaving elongated holes between the larger veins
    • the feeding results in weak plants
    Monitoring
    • during July, watch for holes in the leaves
    Chemical control
    • often controlled when spraying for other pests
Wasps/Hornets/Yellow Jackets

Identification
  • some adult paper wasps are black with yellowish-white markings; others are black with bright yellow markings
  • a colony consists of workers (sterile females), drones (males) and the queen
  • only females have the stinger
  • wasps are hunters and are useful in controlling caterpillars and flies, but they can become pests in the berry fields
Life cycle
  • warm, dry springs produce larger wasp problems in August than do wet, cool springs
  • in spring, the fertilized queen emerges from hibernation
  • she chooses a good spot (a hole in the ground, such as a mouse burrow, a tree branch, bush, under the eaves or in the walls of a building) and begins to build a nest by chewing wood fibers into a pulpy mass
  • the queen lays eggs which hatch into legless, blind larvae
  • larvae last 2 weeks, then pupate
  • in 3 weeks, adult females emerge and begin to tend the queen
  • in August, male and new queen cells are produced
  • in early fall, the males and new queens emerge, mating takes place on the wing
  • males die and fertilized queens overwinter in protected sites like stumps or hollow logs
  • the nest is abandoned and never used again
Damage
  • wasps are attracted to the ripe or injured fruit as a source of sugar and moisture
  • dangerous to pickers as the sting is painful and ,in some cases, may cause an allergic reaction which could lead to death
Cultural control
  • prompt harvesting of ripe berries and clean picking practices
  • hang a piece of meat or fish over a bucket of water with detergent in it; wasps will take a mouthful and fall into the water and drown
  • 2 litre soda pop bottle with about 5 cm of soda pop left in the bottom attracts wasps into bottle
  • basin or some other shallow container, with a few inches of water in it, add syrup (like maple); the insect is drawn to the syrup and drowns in the water
  • set nest on fire with a torch
  • knock nest into a sack and burn it
  • carry out control methods after dusk, after the wasps have settled for the night
  • wear protective clothes (coveralls, gloves hat netting with ends tucked into the collar) when dealing with wasps
  • if necessary to use a flash light, don't hold the flashlight, set it aside to shine on the nest
  • some of the insects will become agitated, leave the nest angry and go for the light, possibly attacking it
Chemical control
  • spray insecticide into the entrance of the nest, do this after dark
  • for ground nests, stuff insecticide soaked cotton or steel wool into the nest
 
 
 
 
For more information about the content of this document, contact Shelley Barkley.
This information published to the web on November 26, 2001.
Last Reviewed/Revised on December 1, 2014.