Raspberry plants are susceptible to infestation from a number of insects and arthropods. Though some raspberry insects are beneficial to crops, others are harmful to the plants and fruit. The first line of defence against pests is to regularly monitor the plants for signs of pest related damage. A number of worms are common in raspberry plants that can damage the foliage, fruit buds and fruit in raspberry plants.
Raspberry fruitworm (Byturus unicolor Say) are among the insects which are likely to inflict heavy damage to raspberry plants. The worms prefer the red and purple raspberry varieties and their adults beetles also cause heavy damage to new buds and foliage of raspberry plants. Raspberry fruitworms are small, ¼ inch, yellow-white, cylindrical worms which create longitudinal holes in the foliage, creating a skeletonised look. The worms also tunnel through the receptacles of the fruits, loosening the berries and leading to fruit drop.
Raspberry Cane Maggot
Raspberry cane maggots are worms that feed on the inside of raspberry canes and cause them to wilt and break in late spring and early summer. The worm feeding in the canes girdles the plant growth. Raspberry cane maggots eat their way downward in the stem below the breaking point and overwinter in the canes. The adult of the worm is a small, greyish fly which start to appear in spring and lay their eggs in new buds and shoots. Best control option is to remove the injured canes as soon as they sighted. There is rarely any need for chemicals as the worms do not infest more than a few canes in every plant.
Raspberry sawfly is a spiny, pale worm which infests the three-fourth matured foliage. The worms eat along the leaf edges and create irregular holes until only the leaf veins remain on the foliage. The worms raise both their head and their tail when they are disturbed. The adult of the raspberry sawfly is a black wasp with red and yellow markings. Best control option for raspberry sawfly is to use recommended insecticide just prior to the opening of the new flowers.