Raspberry Crown Wasp: How To Fight Against This Borer

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Raspberry Crown Wasp

Raspberry Crown Wasp

Raspberry Crown Wasp, also known as The raspberry crown borer (Pennisetia marginata), is a stout-bodied clear-winged moth that resembles a yellow jacket wasp.

It is a common cane-boring insect pest of raspberry in northern Utah.

Although its host range includes all brambles in the genus Rubus, it is only known to cause damage to raspberry in Utah.

Larvae tunnel in the lower cane, crown, and upper roots of raspberry, causing entire canes to wilt and break off at the crown.

Raspberry crown borer infestations are usually not severe, but populations build up slowly over several years, reducing plantings’ vigor and yield.

Adult raspberry crown borers are fascinating black and yellow moths, 10 to 15mm (3/8 to 5/8 inch) in length.

In individual specimens, the yellow color is rather blazing, while at the same time, in others, it is close to white.

They resemble a yellow jacket and are aerial during daylight.

Albeit the name sounds similar to raspberry cane borer, the cane borer is a beetle.

In general, crown borer does not seem to be too severe a pest in some areas, but occasionally sites can be heavily attacked.

Methods of Fighting

There are ways to rid your raspberry patch (or containers) of this pest. Unfortunately, it can take up to two years of permanent treatment to completely break the pest’s life cycle. 

Insecticides containing pyrethrins are considered to be the most effective. 

Apply the solution directly to the plant’s crown early in the spring and in the fall after harvesting.

This will kill the larva heading down the canes to bore into the peak for the winter. 

Insecticides targeted directly at the crown and base of the canes in fall and early spring before the larvae tunnel have an excellent success rate. 

If the infestation is beyond control, dig up, discard the plant in the garbage, or burn it.

Start over again fresh with good quality rootstock and new soil.