Raspberries are generally easy plants to propagate in your yard and garden. Some varieties will actually commandeer your garden and need to be controlled as if they were pests themselves.
Occasionally, insects will overwhelm raspberry plantings – either destroying the plant entirely, or destroying your berries before you can harvest them.
Aphids can typically be found in raspberry plantings on the young tips of canes and on the undersides of foliage. Aphids frequently produce large amounts of honeydew, a sweet waste material which may attract ants.
Honey dew also grows a dark fungus known as sooty mold. Honeydew and sooty mold reduce the quality of berry. Aphids also transmit plant diseases, such as raspberry mosaic virus.
Aphids are not generally a serious problem on raspberries and can usually kept in check with natural controls such as Lady Bugs and Green Lacewings, or with organic insecticides such as Neem based products.
2. Raspberry Fruitworms
Raspberry fruitworms are the larvae of a tiny beetle, known as the raspberry beetle.
The Adult Beetle can grow up to 1/8 inch long, it has a red hued brown body and is covered in tiny, fuzz like hairs.
Adult Beetles feast on the leaves of raspberry and bramble canes, generally the youngest new canes and leaves. When fruitworm populations spike they will attack the entire plant.
Eggs are deposited on or in the proximity of raspberry, blackberry and related bramble bushes. After the larvae hatch, they will feed for some time on the leaves of the plant before making their way into a berry where they will remain until it’s time to pupate.
3. Red-Necked Cane Borers
Red-Necked Cane Borers are a serious pest of raspberries, blackberries and related fruit and brambles.
Adult rednecked cane borers attack foliage, feeding on the upper leaf surfaces during the day leaving irregular holes. Larvae feed on primo canes and form irregular galls from 1 to 3 inches in length which often causes splitting of the bark.
Galls can be found as high as 3 -4 feet up the cane but most are near ground level.
They overwinter in canes, as the larvae molt in the spring, then begin feeding ,creating enlarged cavities within the canes.
Cut out and destroy any canes with this swelling during fall and winter. Don’t compost the canes, destroy them.
You may notice random localized swellings along the canes of your raspberry plants long before you ever see a cane borer. This is a telltale sign of their presence.
This swelling will cause the cane to either die or just break off at this weak point. Infested canes die or become so weakened they cannot support a crop the following season.
The rednecked cane borer adult is a small wood-boring beetle. The slender adults are about 1/4 inch long; they are all black except for an iridescent coppery-red to golden neck.
4. Raspberry Cane Borer
The raspberry cane borer adult is a long-horned beetle, slender, measuring about 1/2 inch long.
It is similar in appearance to the rednecked cane borer and the two are frequently confused with one another. It has a yellow-orange thorax with several black dots, the body is black with two long antennae. The larva is white and legless , it attains a length of about 3/4 inch.
Raspberry cane borer habits and modes of controlling them do not differ from that of the redneck cane borer
When inspecting your plantings, particularly in early summer and late spring look for wilted tips. Prune any wilted tips back, cutting the cane 5 – 6 inches below where the wilting stops. The section you’ve pruned back should contain the larvae.
Destroy any tips you’ve pruned back, do not compost them – destroy them. Continue to maintain scouting the following spring for any signs, in particular wilting tips, and continue to prune them out as well.
5. Raspberry Crown Borer
The adult resembles a yellow jacket, but actually is a moth. The adult raspberry crown borer differs from yellow jackets in that it has noticeable scales on both its body and wings.
Unlike most moths it is not nocturnal, it is a day flier that is active in late summer and early Autumn. The larva are cream colored and are the stage that causes the most extensive damage.
Moths can emerge anytime from early summer through early Autumn and lay their eggs singly on the undersides of leaves. The eggs will take up to two months to hatch in ideal conditions they can hatch in as little as one month.
The larvae will crawl down the cane and tunnel to the soil. They form a small blister on the side to the cane in which they will overwinter. Come spring they will begin tunneling into the cane. Their second overwintering is also passed as a larva within the roots.
They pupate within the canes during the second summer. It is not uncommon to have several generations at varying stages within a planting simultaneously.
Raspberry crown borer symptoms include prematurely cane death, spindly growth, and incomplete leaf development as well as reduced leaf size.
Evidence of crown borer presence includes sawdust like frass near the base of infested canes, swelling , also at the base of the canes, or tunnels within the canes that you may notice when pruning.
Raspberry crown borer control , as well as control of most raspberry pests should include the removal of any wild raspberries or similar brambles in the vicinity. When pruning look for tunnels in the base of canes, this is tell tale sign of their activity. Infested canes and crowns should be removed, and destroyed.
Bacillius thuringiensis [Bt] is highly effective against the larvae stages of all pests of raspberry plants and should be applied as soon as the larvae are first noticed or suspected.
Neem based Products, such as Azatin or Azadirachtin [extract of the neem seed-] prevents the larvae from developing normally and is also a good alternative for later larval stages. These products degenerate rapidly in nature and need to be reapplied frequently.
Related: Growing Hydroponic Raspberries
6. Japanese Beetles
Japanese Beetles are common pests of Raspberries in many areas. They will frequently and rapidly devour the foliage on raspberry plants. A serious infestation can rapidly skeletonized plants and destroy any chances of a raspberry harvest.
Hand picking is sometimes feasible depending on the size and number of your bushes. They are large enough where a shop-vac filled with soapy water is also a workable method, if the shop vac is too powerful you may also do some damage to the plants.
Milky Spore , which is a nematode will kill any grubs and reduce the number of adults that will emerge later to feast on your raspberries and other plants.
Milky spore is slow to get started – it may take several seasons to get going but one application can last over a decade.
Read more on Japanese beetles.
7. Spider Mites
Spider Mites are another Raspberry pest. They damage plants by sucking sap from the foliage.
Light infestations may go unnoticed. Heavily infested plants take on a spotted appearance, and the plant gradually yellows. In many cases, the leaves will drop off after the characteristic fading or yellowing. Badly infected plants will usually have a fine cobwebby appearance on the foliage.
Make a mix of insecticidal soap and water [As per label instructions, some require dilution – some don’t]. Spray all leaf surfaces where mites could possibly be hiding. It’s preferable to do this in the morning or early evening as the soap can actually damage the foliage in hot dry conditions.
Don’t allow the soapy solution to dry completely, rinse it off with a second spray of clean water to remove residual soap that could damage or leave behind an inhibitive film on the plant surfaces.
Repeat this process weekly until you no longer find mites this same process works for aphids as well.
8. Tarnished Plant Bugs
Tarnished Plant Bugs feed on young berries, buds and flowers, and are not easily controlled.
It is sap-feeding insect which attacks a wide range of plants, raspberries are on its menu. They carry fire blight disease and infect plants as they feed. Black spots and pitting can be seen on the stem, tips, buds, and fruit. Most damage takes place just after petal fall.
Found to be resistant to many forms of insecticides, Bioneem has proven highly effective against tarnished plant bug.
Azatin or Azadirachtin [extract of the neem seed- See:Bioneem], prevents the larvae from developing normally and is also a good alternative for later larval stages. These products degenerate rapidly in nature and need to be reapplied frequently.
Kaolin clay acts as a barrier that repels insects and disguises the host plant by coating it with a harmless white film.
Insects, unable to recognize their favorite plants when treated with kaolin clay simply move on. It is frequently used on fruit trees, but works well in vegetable gardens as well.
Bacillius thuringiensis [Bt] is highly effective against the larvae stage and should be applied as soon as the larvae are first noticed or suspected.
Thrips can infest and build up on numerous garden plants. But are seldom seen due to their minute size (Average of 0.04 inch long) as well as the fact that they spend most of their time concealed between foliage and embedded in flowers.
Thrips are among the most abundant insect pests of ornamental plants, many varieties of vegetable plants, small fruits and berries.
Numerous beneficial insects are useful in suppressing thrips. These include lady bugs, minute pirate bugs, ground beetles, and spiders.
The most effective control for thrips is neem oil. It’s effectiveness is based on several modes of action.
It disrupts insects’ hormonal balance so they die before they molt to the next life stage. It suppresses their desire to feed and also repels in areas that have been sprayed.
10. Squash Bugs
Squash Bugs generally attack cucumbers and related squash and melons, but are also an occasional and rare pest of blueberry plants as well.
11. Vinegar Flies
Vinegar Flies, sometimes mistaken for fruit flies are also an occasional problem. They generally attack ripening and decaying fruit.
Leaving berries unharvested will attract these pests, and ensure the return of another generation if left unchecked. Infestations can generally be controlled by keeping berries from over ripening – harvest frequently.
Simple home made fruit fly traps will also work – some fruit juice in a covered cup with small holes for the flies to enter and drown will suffice.
They find their way in but rarely find their way out. Overdoing it with the traps can actually draw more flies to your garden and only serve to compound the initial problem.
Birds, although not an insect, are a frequent problem when growing berries, they like berries as much as people do and will feast on your crop whenever the opportunity arises. See: Bird Deterrents
Related: Best Raspberry Garden Companions