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Beginner

Scientific Name: Oecanthus species, (Order: Orthoptera; Family: Gryllidae)

Identification:

• Adults and nymphs are very similar in form and colour.
• Pale, whitish-green colour, slender and have a flattened appearance with long hindlegs.
• Young nymphs measures about 6 mm and adults reach up to 25 mm in length.
• Antennae are longer than their bodies and they have a small head.
• Adults feature transparent wings, which they fold over their backs.
• The snowy tree cricket has black spots on the first and second antennal segments.
• Damage to raspberry plants is mostly confined to the canes.

Often Confused With
Mechanical Damage
Winter Injury

Period of Activity
Tree crickets have one generation a year and overwinter as eggs. Eggs hatch at the end of May or early June and nymphs and adults remain present until late September. Most egg- laying occurs between the end of August and the end of September.

Scouting Notes
In spring, search fruiting canes for the characteristic rows of puncture wounds from snowy tree cricket. During midsummer, scout the field for nymphs and adults to determine infestation levels and to decide if insecticides are needed. In the late summer, examine primocanes for puncture wounds.  

Thresholds
Not established.

 

Advanced

Scientific Name: Oecanthus species, (Order: Orthoptera; Family: Gryllidae)

Identification:
Several different species of tree crickets affect raspberry plants in North America, including the snowy tree cricket, Oecanthus fultoni. The adults and nymphs are very similar in form and colour. They are a pale, whitish-green colour, slender and have a flattened appearance. Their hindlegs are long, much like those of common field crickets. Tree crickets range in size from 6 mm as small nymphs up to 25 mm as adults. Their antennae are longer than their bodies and they have a relatively small head.  The adults also feature transparent wings, which they fold over their backs. The snowy tree cricket has black spots on the first and second antennal segments.

The damage to raspberry plants is mostly confined to the canes. Damage occurs when adults lay eggs in the primocanes. The female chews out a small portion of the bark and then inserts her ovipositor into the hole to lay an egg. This process is repeated several times leaving a zipper-like scar approximately 25-70 mm long. Eggs are yellow, oblong and approx 3 mm in size. They are easily observed when the cane is sliced lengthwise along the oviposition scar. This injury leads to weakened canes and an increased risk of cane diseases, winter injury and breakage.

Often Confused With

Mechanical Damage
Damage inflicted on canes during mechanical harvesting or by other machines.

Winter Injury
The portion of the cane above the oviposition scar will wilt and die, which gives the cane a similar appearance to one damaged by winter injury. Look closely for the boundary between healthy and dead or wilted tissues and search for the typical zipper-like oviposition scar.

Biology
Tree crickets have one generation per year, overwintering as eggs. The nymphs hatch in late May and early June. Nymphs are mainly predators and feed on aphids, other soft-bodied insects, and fungi. Tree crickets have five nymphal instars which means they moult five times before turning into adults in August. By midsummer, both nymphs and adults are present in raspberries. They feed on fruit, leaves and flower parts, but this feeding does not cause significant damage to the plants.

Between the end of August and the end of September, female tree crickets chew round, puncture-like holes into the canes. The female then pushes her ovipositor into the hole to lay an egg. These wounds are arranged into single rows on each cane and run down the cane lengthwise. They create the appearance of a scar that measures between 25 and 75 mm in length and contains between 30 and 80 eggs. Eggs are yellow and about 3 mm in length. After placing the eggs into the punctures, the female seals the scar with secretions and the eggs are ready to overwinter inside the cane. The puncture wounds are usually found in the top half of the cane. The rows of punctures can damage and structurally weaken the cane above the point of injury, leading to increased winter injury or premature dieback the following summer. The punctures provide an entry site for pathogens, such as the fungus involved in cane blight.

Period of Activity
Tree crickets hatch at the end of May or early June and can remain present until late September. Most egg laying occurs between the end of August and the end of September.

Scouting Notes
In spring, search fruiting canes for the characteristic rows of puncture wounds from snowy tree cricket. During midsummer, scout the field for nymphs and adults to determine infestation levels and to decide if insecticides are needed. In the late summer, examine primocanes for puncture wounds.  

Thresholds
Not established.

Management Notes

• Pruning and weed control to achieve narrow, open rows with good airflow in the canopy will reduce the sheltered environment that favours tree crickets.
• Avoid unnecessary use of insecticides that are harmful to beneficial insects. Some parasitic wasps serve as natural enemies to tree crickets.
• Examine overwintering canes in spring for egg-laying scars. Prune and remove infested canes where possible.