FRUITWORM
Beginner
Scientific Name: Byturus unicolor (Order Coleoptera; Family Byturidae)
Identification
- Adult is a small, light-brown, oval beetle, 4 mm in length.
- Body is covered with small hairs which can be observed with a lens.
- Antennae are short, segmented and clubbed.
- Larvae are slender, white-beige in colour, approximately 6 mm in length, and usually found within the cup of the raspberry fruit.
- Adult fruitworm feed on leaves, buds, and blossoms. Larvae feed on the fruit, causing dry, decaying berry drupelets.
Often Confused With
Geometrids
Raspberry sawfly – damage to foliage
Rose chafer – damage to foliage
Spotted-wing drosophila – damage to fruit
Period of Activity
Adults are active in May and June as raspberry buds emerge. They feed on unfolding leaves and buds on fruiting canes. Larvae are present in developing fruit and are most often observed at harvest.
Scouting Notes
Watch for leaf feeding around developing fruit buds. Their feeding causes elongated holes in the leaf, which sometimes destroys bud clusters. Adults can be detected by shaking bud clusters into a dish or tray but quiet observation is the best way to detect these insects. Scout for adult fruitworms in the early evening and early morning when they are most active. Check wild raspberries around field edges for early signs of activity. .
Thresholds
None established.
Advanced
Scientific Name: Byturus unicolor (Order Coleoptera; Family Byturidae)
Identification
The adult fruitworm is a small, light-brown, oval beetle, 4 mm in length. Its body is covered with small hairs which can be observed with a lens. Its antennae are short, segmented and clubbed. The larvae are slender, white or light brown, approximately 6 mm in length, and usually found within the cup of the raspberry fruit. Adult fruitworm feed on leaves, buds, and blossoms. Heavy infestations can result in complete damage to leaf buds, as well as symmetrical, lengthwise feeding holes on developing leaves. Larvae feed on the fruit, causing dry, decaying berry drupelets. Their presence inside and on the fruit can be a major problem during harvest.
Often Confused With
Geometrids
The term “fruitworm” is often used to describe larvae in the geometrid family, also known as inchworms or loopers. However, raspberry fruitworms are beetles, and their larvae are found inside fruit. Geometrids are moths, their larvae are caterpillars found on the fruit surface.
Raspberry Sawfly
Both raspberry fruitworm beetles and raspberry sawfly larvae feed on foliage. Feeding damage may look similar; however, sawfly larvae are easily spotted on the underside of damaged leaves or in newly developing leave whorls. Larvae of sawfly typically feed on primocane leaves while fruitworm beetles typically feed on buds and leaves on fruiting canes.
Rose Chafer
Rose chafer feeding damage usually results in the destruction of the whole flower bud or blossom. While leaf feeding damage may look similar to that of adult fruitworm, it usually occurs somewhat later in the season.
Spotted-wing drosophila
Larvae of both insects infest fruit. Spotted wing drosophila is much more common. Larvae of SWD are white, pointed at both ends, without a distinct head capsule or legs. Larvae of raspberry fruitworm are light brown, with a brown head capsule and 3 pairs of small legs.
Biology
Raspberry fruitworm adults emerge in early May and begin feeding on young, unopened leaves and buds. The females lay greyish-white, 1 mm long eggs onto flower buds or green, unopened fruit. After hatching, larvae tunnel into the flower bud or the receptacle of the green fruit and then feed their way towards the outside of the fruit. During harvest, the larvae are usually attached to the berry cup on the interior of the berry. Fully grown larvae drop to the ground where they pupate and overwinter to emerge as adults in the next spring.
Period of Activity
Adults are active in May and June as raspberry buds emerge. They feed on unfolding leaves and buds on fruiting canes. Larvae are present in developing fruit and are most often observed at harvest.
Scouting Notes
Watch for leaf feeding around developing fruit buds in spring. Feeding causes elongated holes in the leaf, which sometimes destroys bud clusters. Adults can be detected by shaking bud clusters into a dish or tray but quiet observation is the best way to detect these insects. Adult fruitworms are usually most active in the early evening and early morning. Check wild raspberries around the field edges for raspberry fruitworm and its damage.
Thresholds
None established.
Management Notes
- Insecticides can be applied prebloom for control of this pest.
- Scout for beetles in early evening or early morning.
- If raspberry fruitworm is a known problem, avoid early season red raspberry varieties as they are more prone to infestations.
