Juicy raspberries are tempting treats for many people. However, lush green raspberry bushes dotted with bright red berries are also tempting treats for several species of flying insects. Thrips, sawflies, blackberry psyllids and spotted-wing drosophila feed on ripening and overripe berries and on foliage. Because beneficial bees are needed for pollination, care must be taken when controlling damaging pests.
Identify which black flying insect is attacking the raspberry bushes. Thrips are tiny, cigar-shaped insects that range in colour from white to yellow to brown to black with fringed wings. These poor flyers feed on foliage and fruit, leaving behind damaging scars. Sawflies are thick-bodied black flies, about ¼-inch long. Their larvae consume leaf tissue, resulting in crop loss. Blackberry psyllids are yellow to brown in colour with three brown lengthwise stripes. They feed on foliage, leaving leaves curled and distorted. Spotted-wing drosophila, or vinegar fly, is a small brown fly with black stripes that attacks the ripening and overripe fruit. Sap beetles are small black insects with four yellowish-orange spots on their backs that feed on ripe, damaged or decaying fruit. If you are not sure what is attacking your raspberry plants, take a sample to your local cooperative extension.
Remove all ripe, overripe, damaged and decaying fruit attracting the sap beetles and spotted-wing drosophila.
Place 454gr plastic cups with ½ inch of apple cider vinegar around plants to trap spotted-wing drosophila.
Place blue and yellow sticky traps in and above plants to trap thrips.
Apply diazinon or malathion sprays before blooms set to control most raspberry pests. Read labels carefully, observing all wait times. Use these synthesised controls as a last resort, as they may interfere with bee pollination and delay the harvest, causing fruit to become overripe or begin decaying before being able to be picked.