Insects

Fruit and Foliage Insect Pests

Raspberry Fruitworm (Byturus unicolor): The raspberry fruitworm is a small (1/4”) brown beetle which feeds on the flower buds and leaves of raspberry plants during the spring and early summer. Female beetles lay eggs on the flowers and green fruit. The grubs that emerge are yellowish white, and feed on the fruit, attaining about 3/8” in length. Many of the flowers and fruit can be destroyed by this insect, and the larvae may end up in the harvested fruit, greatly reducing customer appeal.

Management: There is some evidence suggesting that this insect is more of a problem in weedy plantings. If early damage is noted, (e.g., small holes chewed in flower buds and skeletonizing of leaves), cover sprays should be applied prior to bloom. Adults (beetles) tend to be most active and noticeable on plants in the early evening hours. See pest management schedule for recommended materials and timing.

Tarnished Plant Bug (Lygus lineolaris): The tarnished plant bug (TPB) is a small (1/4”) bronze-colored insect with a triangular marking on its back. The immature stage, or nymph, is smaller and bright green, resembling an aphid, but much more active. Both adults and nymphs feed on the developing flowers and fruit, sucking out plant juices with straw-like mouthparts. This results in deformed fruit, with a few to many drupelets not enlarging, depending on the severity of the damage. Such fruit tend to crumble easily, and are generally unmarketable.

Management: Controlling weeds in and around the planting may reduce populations of this insect, but insecticide sprays may be necessary, applied prebloom and repeated after petal fall. If mowing around fields, do so after insecticides have been applied (to control migrating insects). Avoid planting alfalfa (which attracts high populations of TPB) near raspberries. White sticky traps are available for monitoring tarnished plant bug adults. These traps are used as an indication of when plant bugs begin their activity in the spring and a relative indication of their abundance, not as an indication of when to control this insect. Immature TPB (nymphs) are sampled by shaking flower trusses over a flat white surface. Thirty flower clusters should be sampled evenly from across the field (typically 6 clusters at 5 locations or 5 clusters at 6 locations). If 4 or more flower clusters are infested with nymphs (regardless of how many) a spray is recommended. A follow-up spray application may be made after bloom if TPB are still present in high numbers (check harvest interval before selecting material). See pest management schedule for recommended materials and timing. Do not apply insecticides during bloom.

Strawberry Bud Weevil (Anthonomus signatus): The strawberry bud weevil or “clipper” is an important pest of strawberries, but will also attack bramble fruit. This insect is a very small beetle (1/8”) with a copper-colored body and a black head with a long snout. The female weevil chews a small hole in unopened flower buds and lays an egg in the hole. She then girdles the stem just below the bud. The flower bud dries and dangles from the stem, eventually falling to the ground. The immature weevils, or grubs, develop in the girdled buds, emerging as adults in the early summer, and then migrating to wooded areas. These insects are not always present and may only cause minimal damage in raspberries.

Management: Examine the plants before bloom, and look for dead or clipped-off buds. Insecticides which are applied prebloom for control of raspberry fruitworm may also control this insect. See pest management schedule for recommended materials and timing.

Two-Spotted Spider Mites (Tetranychus urticae): Spider mites are very small (1/50”), insect-like creatures that feed on raspberry foliage, sucking out plant juices and causing a white stippling or bronzing of the leaves. Under heavy infestations, leaves will turn brown and be covered in a fine webbing. Adults may also move onto the fruit, reducing consumer appeal by their presence. There is currently little available for chemical control of this pest.

Management: Several companies commercially produce predatory mites which feed on spider mites. These predators can be released in raspberry plantings when mite populations are low, before the population gets out of control, and may provide some control of spider mites. It is important, however to encourage natural enemies of spider mites by reducing the use of pesticides which harm natural enemies. See source list at end of this guide for predatory mites. Spider mite outbreaks have also been associated with high levels of nitrogen fertilization.

Aphids: Aphids are small, pear-shaped, soft bodied insects which feed on plant sap with straw-like sucking mouthparts. Several species of aphids ranging from 1/16” to 1/8” in size, and dull yellow to bright green in color feed on raspberries. Most are wingless and slow moving. These insects tend to congregate on the underside of leaves, where their feeding causes the leaves to curl downward and be deformed. The most damaging aspect of aphid feeding is the spread of viruses. Aphids will take in a virus from infected plants, and later inject it into healthy plants. The virus then spreads throughout the plant, resulting in symptoms such as mosaic, leaf curl or stunting.

Management: To reduce the incidence of aphids and the transmission of viruses, start with certified virus-free plants; eliminate all wild brambles from within 600 feet of the planting; apply insecticides when aphids are first noticed in a planting; and rogue out all plants which exhibit virus symptoms. See pest management schedule for recommended materials and timing. The varieties Canby, Titan and Royalty are resistant to aphid feeding.

Japanese Beetles (Popillia japonica): Japanese beetles are about 1/2” long and copper-colored, with metallic green markings. They feed on raspberry foliage, skeletonizing the leaves during the mid and late summer. The larvae, or grubs, live in the soil, feeding on roots of grasses until late fall.

Management: The beetles can be controlled with insecticide sprays. However, pay close attention to days to harvest restrictions if fruit is present. Traps are available which use a sex and/or feeding attractant to capture the bugs in a can or plastic bag, but such traps generally do not provide adequate control. Place traps at least 100’ away from the planting. Traps placed within a planting may cause localized damage from beetles which are attracted to, but don’t fall into the trap.

Yellowjackets: Yellowjackets (aka hornets or wasps), are black and yellow stinging insects. They are closely related to the larger bald-faced hornets. Both groups of these insects are very aggressive and will sting with little provocation.

There are several species of these wasps found in the Northeast and, depending on the species, may build underground nests, large paper nests in trees or on houses. Many scavenge food, often dead insects or pieces of flesh from dead animals. Yellowjackets also have a great fondness for ripe fruit and can be found on pears, apples, raspberries, etc.

This fondness for fruit makes this insect a severe nuisance pest in raspberries, especially fall bearing varieties. They are a danger and annoyance to pickers. To help discourage the yellowjacket from feeding on raspberries, be sure to harvest berries as soon as they begin to ripen, even though there may be only a few early berries. Once the yellowjackets have discovered the berries, it is almost impossible to discourage them.

Management: Insecticide sprays for control of yellowjackets are not effective or recommended unless you know where a nest is and can eradicate it with a household hornet spray. This is best done in the evening when most of the members of the colony are in the nest. Yellowjackets can be discouraged by sanitation, which is regular and thorough, picking of all berries as soon as they begin to ripen, and frequent removal of overripe fruit and fruit debris.

There are many yellowjacket traps on the market, and various baits have been used with some success. Our (eastern) species of yellowjackets do not respond to trapping as well as western species. Different baits and traps may have to be tried to determine if any traps/baits will work in a particular raspberry planting. If traps are to be used, the key to success is to get the traps out early. Once yellowjackets have found the ripened fruit, the traps will probably not be of much help.

Potato Leafhopper (Empoasca fabae): Nymphs and adults are small (1/8”) green soft bodied insects. They move very quickly, often sideways, when disturbed. The potato leafhopper feeds on the underside of leaves leaving small chlorotic areas and causing a downward cupping of the leaves. Most feeding is on the upper, more succulent leaves on primocanes and often causes a stunting of those canes.

Management: This pest does not overwinter in New England but is brought up every year from the south on storm fronts. Insecticide applications may be needed when damage is observed. Plants recover quickly once these applications are made and normal growth resumes.

Brown marmorated stink bug (BMSB) (Halyomorpha halys): Adult BMSB are approximately 3/4 inch long and are shades of brown on both the upper and lower body surfaces. They are the typical “shield” shape of other stink bugs, almost as wide as they are long. To distinguish them from other stink bugs, look for lighter bands on the antennae and darker bands on the membranous, overlapping part at the rear of the front pair of wings; a black and white triangle shaped pattern along the edge of the abdomen; and rounded shoulder tips. Masses of 20-30 eggs are laid on underside of leaves. The 5 nymphal stages range in size from 1/8 - 1/2 inch. Nymphs and adult BMSB feed on many hosts including small fruits, tree fruits, vegetables, ornamentals, and seeded crops such as corn and soybeans. BMSB feeds by puncturing the fruit with piercing/sucking mouthparts, and injecting saliva which allows the insect to suck up the plant material through its mouthparts.

BMSB has become a serious insect pest throughout much of the mid-Atlantic states and southern New York. BMSB is known to be in all New England states and since 2014 has become an agricultural pest in southern New England.

Spotted wing Drosophila (SWD) (Drosophila suzukii): SWD are invasive vinegar flies (fruit flies) that can attack unripened fruit. Female SWD cut into intact fruit with their serrated ovipositor to lay eggs under the skin. This allows larvae of SWD to be present during ripening, leading to a risk of detection in ripe fruit after harvest. There is a greater risk of fruit contamination at harvest from SWD compared with native species that lay eggs only in already-damaged and rotting fruit. SWD seem to prefer brambles over all other hosts.

Management: Although flies are relatively easy to kill with insecticides, keeping berries free from infesation can be difficult because of near constant pressure of countless flies. Pest pressure is lower earlier in the season, during harvest of summer-bearing varieties, compared to very high pest pressure during harvest of fall-bearing varieties. To date, only frequent and repeated insecticide application throughout the ripening and harvest period have proven effective. Sprays would be recommended as a preventative measure on any fruit starting to ripen in the first weeks of August. Weekly coverage may be adequate under low pressure, but twice weekly sprays may become necessary for high pest pressures. Choose insecticides based on efficacy and preharvest interval and rotate between IRAC classes. Add 4-16 ox NuFilm P/100 gal with all materials to improve residual efficacy.

Cane Insect Pests

Cane Borers: Raspberries are attacked by two types of cane borers. The raspberry cane borer is a 1/2” long, slender black beetle with an orange band just below the head and has long antennae. The female beetles girdle the tips of young raspberry canes by chewing two rings, about a half inch apart, around the stems about 6" to 8” below the top. An egg is inserted into the cane between the two girdled rings. When the larvae, or grubs, emerge, they feed inside the cane, tunneling downward, and eventually destroying the cane. Soon after the cane tips are girdled, they wilt, blacken, and may fall off.

Management: As soon as the wilted tips are noticed, they should be cut off several inches below the lowest girdle mark. Remove the infested tips from the field and destroy them. Also eliminate any wild brambles near the field which may be harboring this pest.

The red necked cane borer is 1/4” long, slender, black with a “coppery” neck. Unlike the raspberry cane borer, it has short antennae. The red necked cane borer also causes a different sort of damage. The females insert an egg into young canes, usually within 10” of the base of the cane from late spring through mid-summer. They do not girdle the cane, but the presence of the egg, and later the grub, causes a swelling in the cane which can vary in length from 1/2” to nearly 3”. Larvae feeding within the canes weakens them and many may break off. Remove any canes showing swelling near the base.

Root and Crown Insect Pests

Raspberry Crown Borer (Pennisetia marginata): The adult phase of raspberry crown borer is an attractive clear-winged moth which resembles a wasp. These moths lay eggs on the underside of raspberry leaves in late July and August. When the eggs hatch, the young larvae crawl down the cane and into the soil to overwinter. The following spring, they bore into the base of the raspberry canes and feed on the plant tissue. This feeding interrupts the flow of water and nutrients to the cane, causing them to wilt and become weak and spindly. Early symptoms may include browning of the leaf margins on new canes. Eventually, the entire crown may die. Infected canes are easily pulled out of the ground.

Management: Elimination of all wild brambles in the area can reduce local populations of this pest.