Sap beetles (Coleoptera: Nitidulidae) are conspicuous insects that feed on flowers, fruits, sap, fungi, stored products, and decaying and fermenting plant tissues from diverse trees and crops, including strawberries. Sap beetles work in association with yeasts and other fungi causing the fermentation and decay of infested plant parts (Figure 1). They also transport a variety of microorganisms that cause plant diseases, and a few species behave as predators of various ornamental pests (Dowd and Weber 1991). Sap beetles are often considered minor pests; however, their main impact is due to the contamination of products caused by adults and larvae.
Sap beetles, sometimes called nitidulids or picnic beetles, undergo four life stages: eggs, larvae, pupae, and adults. Eggs are white and small. Larvae are white with a light brown head and have three pairs of legs. They are about the same size as the adults (Figure 2). Adult size depends on species, but most are 1/10–1/2 inch (2–15 mm) long and 1/4 inch (6.5 mm) wide. Adults are oval shaped, usually black, brown, or grayish, with clubbed antennae (Figure 3).
Strawberry sap beetles are a common pest that can wreak havoc on ripening strawberry crops These tiny beetles bore into ripe and overripe strawberry fruits, marring their appearance and causing decay. Left uncontrolled, sap beetle damage can quickly escalate, ruining a substantial portion of your harvest
Getting rid of sap beetles in your strawberry patch takes persistence, but is possible with diligent monitoring and a combination of organic control methods. In this article, we will cover how to identify sap beetles, why sap beetle control is so important for your strawberry harvest, and effective ways to get rid of strawberry sap beetles organically.
Identifying Strawberry Sap Beetles
The first step is confirming that sap beetles are indeed the culprits damaging your ripening strawberries Look for these key signs
- Tiny dark beetles less than 1/8 inch long on ripe or damaged berries
- Small, round holes bored into the sides of fruits
- Tunneled cavities with brown frass inside berries
- Shriveled, decaying berries with sap beetle larvae inside
Adult sap beetles are oval, flattened, dark brown to black insects. They have antennae with clubs on the ends and short wing covers. They are attracted to fruits damaged by other pests, feeding and laying eggs in the decaying tissue. Their larvae then tunnel deeper into the fruits, causing further internal damage.
Why Sap Beetle Control is Critical
At first glance, sap beetle damage may seem minor. However, without control measures in place, sap beetle populations can increase exponentially, progressively ruining more and more of your harvest. Here’s why diligent sap beetle control is so important:
- They rapidly reproduce, with each female laying dozens of eggs
- Feeding and egg-laying causes accelerated fruit decay
- Larval tunneling can destroy whole fruits from the inside out
- Damage makes fruits unmarketable due to poor appearance
- They may transmit fruit rotting fungi as they feed
Controlling sap beetles promptly keeps your strawberry harvest sellable and prevents population explosions that can be difficult to manage
Effective Organic Methods to Control Sap Beetles
Here are some of the most effective organic approaches to get rid of sap beetles in your strawberry patch:
Remove Infested Berries
- Check ripe berries daily and discard any with sap beetle damage
- Remove and destroy overripe or rotten fruits that attract sap beetles
- Bury discarded fruits deep or seal in plastic bags to kill larvae inside
Use Traps
- Set out traps with fermenting baits like wheat dough, vinegar, or ripe fruits
- Place traps along patch edges to intercept incoming beetles
- Empty and refresh baits every 2-3 days for continued effectiveness
Maintain Diligent Harvesting
- Pick berries daily as they ripen to avoid overripe fruits
- Wash off berries immediately after picking to remove eggs/larvae
- Keep ground and plants free of debris to eliminate hiding spots
Apply Row Covers
- Cover rows with lightweight fabric row covers to exclude beetles
- Secure edges tightly with soil or rocks to prevent entry
- Remove covers when berries ripen to allow pollination
Use Kaolin Clay
- Spray fruits with kaolin clay coatings which deter sap beetle feeding
- Reapply after rainfalls to maintain protective barriers
- Follow all label directions when applying to edible crops
When Pesticide Use May be Warranted
While organic control methods are ideal, sometimes pesticides are needed to quickly knock down heavy sap beetle infestations. Consider chemical control options if:
- Trap crops and sanitation fail to protect ripening fruits
- More than 10% of your crop shows sap beetle damage
- Infestations persist as harvest reaches its peak
- Removal of damaged fruits cannot keep pace with new damage
If pesticide application is necessary:
- Treat at first signs of damage, before fruits are ripe
- Select targeted, low toxicity products labeled for strawberries
- Carefully follow all label instructions for dosage and timing
- Combine with non-chemical methods for most effective control
The key is being vigilant, scouting for early signs of sap beetle damage. Promptly removing infested fruits, maintaining cleanliness, and using row covers and traps can keep sap beetle populations in check. But sometimes pesticides may be needed to avoid substantial crop losses when dealing with heavy infestations.
Preventing Future Sap Beetle Issues
Once you get an active sap beetle infestation under control, focus on prevention to avoid recurrent issues:
- Install row covers early, before fruits start ripening
- Eliminate weeds, debris, and alternate beetle hosts around your planting
- Apply kaolin clay coatings preventatively
- Maintain a strict harvest schedule, picking all ripe fruits daily
- Scout regularly and take action at the first sign of damage
- Rotate strawberry planting sites each year to disrupt pest cycles
With diligent monitoring and a combination of organic control methods, you can keep strawberry sap beetles in check and enjoy bountiful harvests of beautiful, damage-free berries. Don’t allow these tiny pests to take over your strawberry patch!
Sap Beetles in Florida
There are more than 4,500 species of sap beetles, with about 165 species in North America. Twenty-one genera have been reported in Florida including Carpophilus, Stelidota, Glischrochilus, and Epuraea (Myers 2001). Species in these genera are typically the most problematic agricultural pests. In Florida strawberries, Potter et al. (2013) found 9 species in seven east Hillsborough County fields (Plant City, FL). These species in order of abundance are Epuraea (= Haptoncus) luteolus, Lobiopa insularis, Carpophilus fumatus, Carpophilus humeralis, Carpophilus freeman, Stelidota geminata, Stelidota ferruginea, Carpophilus mutilates, and Colopterus insularis.
Approximately 94% of the sap beetles were the top three species: E. luteolus, L. insularis, and C. fumatus; however, consideration must be given to all species. Correct identification should be followed by preventive methods to control damage by sap beetles.
Sap beetle adults fly into strawberry fields from surrounding fields or wooded areas. In temperate regions, flights occur after beetles overwinter and when strawberries begin to ripen as temperatures exceed 16°C (67°F) (Blackmer and Phelan 1995; Loughner et al. 2007). In Florida, sap beetles are common later in the harvest season (February–March) as weather warms and as attractive, damaged strawberries in fields accumulate (Price and Nagle 2013).
Both adult and larval sap beetles attack and feed on fruits. Longevity of adults is approximately 2 to 2½ months. A few hours after mating, eggs are usually laid on or under damaged or discarded fruit, although some species lay eggs in soil. After hatching from eggs, larvae burrow up into berries, feeding on the flesh for approximately 1½ weeks. Larvae then fall to the ground, burrow into the soil, and pupate. Sap beetles have a wide range of feeding habitats but most feed on fruits and other plant parts that are ripening or decomposing or on fungus that is growing on ripe and overripe plant parts (Peng and Williams 1990; Myers 2001).
There are two types of damage inflicted by sap beetles: direct (feeding cavities or holes) and indirect (dissemination of microorganisms). Cavities also serve as egg-laying sites. Larvae inside strawberries usually go unnoticed until the fruit begins to decompose as a result of the damage. Because overripe strawberries are attractive to sap beetles, damage is often greatest during harvesting when pickers leave ripe and overripe strawberry plants in the field or if fruit is discarded in ditches or weedy field margins (Figure 4).
Sap beetles are not usually economically important in field, fresh-market strawberries; however, when overripe strawberries are harvested for processing, sap beetles may infest the fruit and make the product unmarketable. Considering the ecology of sap beetles, the following practices are recommended.
If possible, avoid planting strawberry next to wooded areas. For fields next to wooded areas, monitoring when sap beetles are flying into fields is important for timing controls. Place pitfall traps (plastic cups buried flush with the soil surface and partially filled with soapy water) or “trap buckets” (an approximately 1 gallon bucket partially filled with soapy water and containing an 8 oz plastic cup with fermenting banana, strawberry or other fruit or bread dough placed in the bucket) outside field borders to intercept immigrating sap beetles.
Pick berries frequently, before they become overripe. Remove all damaged or overripe fruit from field areas, but do not dispose of them in weedy field margins, especially in hot weather. Picking and placing infested fruit into the row middles may be a reliable alternative method to reduce numbers of adults in the field (Potter 1995). Fruits decompose faster in between rows than sap beetles can complete their life cycles, thus interrupting their life cycle. Keep in mind that fermenting berries may attract sap beetles capable of migrating from long distances (Potter 1995). Similar sanitation practices should be done with other fruits and vegetables.
A nematode parasite of one sap beetle species has been documented (Dowd et al. 1995). A commercially-available beneficial nematode (Steinernema carpocapsae) (eg, Millenium, BASF Corp.) is effective against soil-dwelling stages of other beetle pests of strawberry and may provide suppression of sap beetles.
A small, parasitic wasp, Brachyserphus abruptus, has been reared from multiple sap beetle species, and reduced adult emergence by 99% when young sap beetle larvae were infected (Williams et al. 1992).
Apply recommended insecticides when conditions justify. Insecticides recommended to control sap beetles are Assail (acetamiprid), Brigade (bifenthrin), Danitol (fenpropathrin), and Rimon (novaluron) (Price and Nagle 2013). Rimon is an insect-growth regulator and is only effective against sap beetle larvae. Rimon may be tank mixed with one of the other listed products that is effective against adult sap beetles.
For biopesticides, products containing azadirachtin or neem oil (eg, Azatin, Neemix, Trilogy) will control larvae and pupae, and will repel and deter feeding by larvae and adults. Fungi that attack insects (entomopathogens) (eg, Mycotrol O, Naturalis, PFR-97) are effective against larvae after repeated applications and when relative humidity is high. Products containing pyrethrins may also be used.
Insecticide use is limited by frequent harvests and pre-harvest intervals indicated on labels for specific products. Application(s) should be made when sap beetle adults are first detected. Follow insecticide label instructions for best results.
Top 3 strawberry pests and what to DO about them
FAQ
How do I get rid of strawberry sap beetles?
Baited traps are sometimes recommended for mass-trapping strawberry sap beetles. Baits can include various plant products that emit a fermenting or rotting odor. Whole wheat bread dough was used by Rhainds and English-Loeb (2002).
How do you get rid of strawberry beetles?
The best, long-term way to control these pests is to caulk and seal the outside of the house to prevent them from entering. The best method of controlling the weevils inside the home is to vacuum them up.
How to get rid of spittlebugs on strawberries?
To eliminate spittlebugs on strawberries, start by blasting them off with a strong stream of water from a hose. If the infestation is severe, consider using insecticidal soap or neem oil, but always test a small area first to ensure it doesn’t harm the plants.
How to keep sap beetles away?
Sap beetles are attracted to fermented plant juices and damaged corn. Do not let corn become overripe and rot in the field. Remove overripe or damaged corn quickly and keep cull piles away from the field. If possible, avoid planting near fruit or vegetable dump sites or compost areas.