As a gardener, I often get questions from readers about pest problems affecting their plants. One common issue I hear about is the presence of lerps on American elderberry shrubs. Lerps are tiny sap-sucking insects that can seriously damage elderberry shrubs if left uncontrolled. In this detailed guide I’ll walk you through everything you need to know about getting rid of lerps on American elderberry shrubs.
What are Lerps?
Lerps are small, sap-sucking bugs that belong to the insect order Hemiptera. They are related to aphids, scales, and other piercing-sucking insects. Lerps use their straw-like mouthparts to pierce plant tissues and feed on sap.
These sap-feeders produce a protective covering over themselves made of wax and honeydew secretions. This covering shields them from predators and weather while allowing them to feed safely on the plant. The coverings appear as small white or brown bumps on the stems and leaves.
If lerps are present in high numbers, they can weaken the elderberry shrub by extracting large amounts of sap Their sugary honeydew secretions also promote the growth of sooty mold fungus which coats the leaves, blocking sunlight Left uncontrolled, lerps can seriously impact the health and productivity of elderberry shrubs.
Identifying Lerp Infestations
To treat lerps, you first need to check your elderberry shrubs carefully and confirm their presence. Here are some telltale signs of lerp infestations
- Small white or brown bumps clustered on stems and leaves
- Sticky residue or droplets on leaves (honeydew secretions)
- Sooty black mold growing on leaves and stems
- Distorted or curled leaves
- Presence of ants which feed on the honeydew
Examine both surfaces of leaves as well as young shoots and branches. Lerps often gather where tender new growth is emerging. If you spot any of these signs, take action to control lerps before they get out of hand.
Removing Lerps Manually
For light infestations confined to a few branches, manually removing the lerps may be sufficient. Take a soft cloth or toothbrush and gently rub off the scale-like coverings. Alternatively, use a strong stream of water to wash off lerps. Be sure to check both sides of leaves.
Any lerps you remove should be dropped into a container of soapy water or rubbed with alcohol to kill them. Manual removal works best when lerp populations are low before they have a chance to spread.
Using Horticultural Oils
Horticultural oils like neem oil are highly effective at smothering soft-bodied insects like lerps. The oils block the pores in their exoskeleton, eventually killing them. Mix a horticultural oil product with water according to label directions.
Spray the oil solution thoroughly over infested elderberry shrubs, especially new growth. The coating action of the oil also helps deter reinfestation. Aim for good coverage of both upper and lower leaf surfaces where lerps gather.
Applying Insecticidal Soap
Insecticidal soaps containing potassium salts of fatty acids can be used against lerp populations on elderberry shrubs. When applied directly, the soap solution penetrates the protective coverings and kills the insects inside.
Spray insecticidal soap liberally over all parts of the infested shrub. Two or three applications a week apart may be required to disrupt the lerp life cycle. Avoid spraying open flowers to prevent harming pollinators.
Releasing Natural Predators
Encouraging beneficial predatory insects is a natural way to control lerps. Lacewings and ladybugs feed on lerps and keep their numbers in check. You can purchase live ladybugs or lacewing eggs and release them onto infested elderberry shrubs. The larvae will start feasting on lerps right after hatching.
You can also attract native ladybugs and lacewings by planting nectar-rich flowers like daisies and cosmos nearby. Creating a diverse garden ecosystem supports natural pest control.
Applying Neem Oil
Like other horticultural oils, concentrated neem oil is extremely effective against soft-bodied insects. It coats their bodies and asphyxiates them. Mix neem oil with water according to directions and spray infested elderberry shrubs, including the undersides of leaves where lerps hide.
Neem oil also disrupts the growth and reproduction of insects. Repeat applications may be required for complete control. Neem oil can harm beneficial insects, so avoid spraying open flowers.
Using Systemic Insecticides
For severe lerp infestations, systemic insecticides that are absorbed by the plants can be very effective. Products containing imidacloprid or acephate are taken up through the roots and make the plant tissues toxic to lerps feeding on them.
Apply systemic insecticides as drenches around the base of the elderberry shrub according to label directions. Systemics provide protection for several weeks. Exercise caution with these chemicals and avoid applying them to edible plants.
Pruning Infested Areas
Pruning away heavily infested stems and branches can help reduce lerp populations. Clip off any sections that are completely coated with lerps. Disinfect pruning shears between each cut with rubbing alcohol. Removing infested wood eliminates large numbers of lerps and their eggs.
Tips for Prevention
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Keep elderberry shrubs healthy with regular feeding and ample watering. Stressed plants are more vulnerable.
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Remove weeds around shrubs to eliminate alternative lerp hosts.
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Wash off lerps early before they have a chance to build up.
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Avoid excess nitrogen fertilization which promotes lerp growth.
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Monitor shrubs frequently and treat at first signs of infestation.
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Remove and destroy any severely infested branches.
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FAQ
How to get rid of lerps?
How to get rid of psyllids naturally?
How to get rid of elderberry borers?
How do you get rid of aphids on elderberries?
How do you care for elderberry shrubs?
Backfill the planting holes with the displaced soil and water the soil deeply and thoroughly. Water your elderberry shrubs thoroughly once or twice per week to supplement rainfall during the first growing season after planting them. Soak the soil around the entire root area of the shrubs.
When should I prune my elderberry plants?
There are three methods to pruning, but I must note, you shouldn’t prune your elderberry plants until they’re at least three years old. The first method of pruning is only removing the dead or weakened portions of the plant. The next option is to remove 1/3 of the plant each year.
Do elderberries get aphids?
Your plants may also run into issues with aphids. They may be treated with an insecticide or by spraying the plant forcefully with soapy water. The most common diseases to impact elderberries are cankers, rot, and leaf spot. Cankers must be trimmed out of the plant and ensure the infected wood is burned to avoid further spreading the disease.
Do elderberry bushes need weeds?
Elderberry bushes like to have a clean growing space. It’s best to keep weeds down around your plants. By reducing the amount of debris around the plant, you’re increasing airflow and also ridding the area of spaces for pests and diseases to hide.