Cherry Fruit Worms

Garden Insects of North America

Identification / Diagnosis of Cherry Fruit Worm Infestation

Cherry Fruit worms cause severe damage in blueberries, cranberries and Cherries. It causes its injury by boring into the fruit. The larvae bore through the epidermis shortly after they hatch. This early injury can be detected in a few days. The larvae may feed extensively just below the surface. A maturing larva may damage more than one fruit.

The cherry Fruit worm has one generation per year, once the fruits themselves become infested there is no way to kill off the worms which are inside.

All infested fruits must be handpicked and destroyed so that the cherry and cranberry Fruit worms do not migrate to other nearby host plants.

Cherry fruit worm are the larvae of a dark gray moth with brown markings on their wings. The worms themselves are smooth reddish caterpillars with brown heads, they have three pairs of rear legs, and several pairs of stubby smaller abdominal legs. They are frequently mistaken for the larvae of the cranberry fruit worm, but are more reddish in color. The worms grow to about 3/8 inch long.

The adult stage reveals a dark gray moth with brownish markings on the wings. These moths have a wingspan of 3/8 to 1/2 inch. They are nocturnal and rarely seen in daylight, when they hide under leaves and foliage. Adults emerge in early spring and lay their eggs on both the foliage and fruit of host plants. Most larvae will hatch in mid-April and bore into the first fruit they come across.

When larvae are slightly more than half grown, they migrate to neighboring fruits and berries. Frequently boring from one fruit to another. A telltale sign of their presence is a lining of silk at the meeting points of berries within clusters. Upon completion of their larval stage, caterpillars exit the fruit and excavate small burrows in host canes and stems, or the stems of nearby weeds. The caterpillar will remain dormant within these burrows for the remainder of the season and over winter. Come spring they re-emerge as Adults and the cycle of life [and death for you plants] begins again.

Detection of effected fruit is sometimes difficult because there is very little external evidence of the insect’s presence within. Larvae are well hidden inside the berries. look for the presence of silk connecting berries or for pin sized entry wounds near the plant stem of any berries. A premature color change in the fruit is also a visible sign of a possible infestation. Opening some berries may reveal the light reddish colored worms.

Control of Cherry Fruit Worms

Adult moths can be trapped with light traps by night. Parasitic wasps sometimes attack cherry fruit worms as will Lady Bugs.

Neem Oil ,Bioneem and various derivatives of their active ingredient Azadirachtin are an effective Biopesticide that works by interrupting the insect’s growth cycle resulting in its early death.

Spinosad organic pesticide is another biopesticide , correctly termed a microbial pesticide, harmless to humans. Spinosad will interfere with pollinators as well as pests – evening / night time use is advisable.

Bacillus thuringiensisBacillus thuringiensis for controlling Celery worms has proven somewhat effective, it is a bacterium / organic pesticide that is readily available to home gardeners. It’s harmless to people and pets. Apply it at either bloom or petal fall, or both. Bt It is a stomach poison and must be ingested . It is more effective when applied during warm, dry weather while the larvae are actively feeding. Bt breaks down quickly in nature so multiple treatments per season are necessary.

Sprays/Pesticides must be applied in the pre-bloom stage to prevent injury. Do not apply insecticides, even bio-pesticides during bloom time to protect vital pollinating insects. Pesticides such as pyrethroids {Pyrethrin} that are more effective in cool than warm weather will work more efficiently against Fruit worms earlier in the season, and is the recommended early season chemical for most types of worms.

Proper sanitary practices are vital to the health of your garden. Proper sanitation can help to ensure disease-free pest-free and productive gardens. Try to keep the garden free of any diseased dead or damaged plant materials. Remove cuttings from pruning and trimming and either destroy them – if diseased, or send them to the compost pile, don’t send diseases plant material to the compost pile. Leaving rotting fruits and vegetables in the garden is like a written invitation to unwanted pests and diseases.

If a diseased or dead plant part has to be cut, the microorganism that caused the problem is probably on the tool you just used. Like a surgeon, sterilize all tools by washing in soap and water – rubbing alcohol wouldn’t hurt either. If you pinch off diseased plant parts, wash hands before handling any other plants. Keep Weeds under control. Till the soil in the spring before planting to expose and kill larvae that wintered over in the soil.