Life cycle The euonymus caterpillar starts out as an immature egg and ends up as a winged moth in the adult stage.
Female moths are creamy white with black spots on their wings.
They lay their eggs in mid to late July and cover them with a gummy secretion.
The eggs hatch in mid August and the larvae (caterpillars) immediately prepare to survive the winter by concealing themselves under their scale-like egg shells.
Early the following year, the larvae make small webs and start feeding on new leaves.
The webbing increases as the caterpillars grow.
Fully grown caterpillars are about 3/4-inch long.
They construct cocoons in late June that are covered in white webbing and hang side by side off the plants.
The caterpillars pupate inside and emerge as moths.
Non-chemical controls Inspect your plants in mid-May to early June and look for actively feeding caterpillars and webs.
If you catch them early, you can pick them off or prune off the branch tips where the caterpillars are feeding.
Drop the picked-off caterpillars into a can of soapy water to kill them and burn or otherwise destroy the pruned-off branches to stop the caterpillars from spreading.
In July, scout your plants for the scale-like egg masses and scrape or prune them off.
Cocoons can also be snipped off and destroyed to stop the insects from completing their life cycle.
Chemical controls If you have a lot of euonymus plants to take care of, or if the infestation is spreading too fast, you may wish to use a chemical control.
Several reduced-risk pesticides are available to control soft-bodied caterpillars that are less harmful to human health and the environment than the conventional stomach poisons.
These products include insecticidal soaps, dormant oils and pheromone traps.
Pesticides that contain a bacterium that is toxic to the pest, such as B.
t.
, are also considered safer for the environment.
Be sure to read the label carefully and follow all the directions and safety precautions.
After applying a pesticide, check the plants again a few days later to make sure the application was effective.
It may be necessary to retreat.
The key to effective control is to apply the pesticide in the spring while the larvae are still small and before they have done too much damage to the plant.
Follow-up Euonymus caterpillars first begin feeding at the tips of branches and then move inward to cover more and more of the plant with webbing.
The caterpillars are feeding inside the webs and, in some cases, completely defoliate the euonymus tree or shrub.
Euonymus may survive the first defoliation but eventually they will die if the defoliation continues each season.
Keep scouting and observing the health of your eunoymus plants.
Rake up and remove any debris around them to catch any cocoons that may have dropped to the ground.
Prune out any dead branches and keep your euonymus plants healthy by watering and mulching especially during hot weather.
Healthy plants can resist insects and diseases more effectively.
Female moths are creamy white with black spots on their wings.
They lay their eggs in mid to late July and cover them with a gummy secretion.
The eggs hatch in mid August and the larvae (caterpillars) immediately prepare to survive the winter by concealing themselves under their scale-like egg shells.
Early the following year, the larvae make small webs and start feeding on new leaves.
The webbing increases as the caterpillars grow.
Fully grown caterpillars are about 3/4-inch long.
They construct cocoons in late June that are covered in white webbing and hang side by side off the plants.
The caterpillars pupate inside and emerge as moths.
Non-chemical controls Inspect your plants in mid-May to early June and look for actively feeding caterpillars and webs.
If you catch them early, you can pick them off or prune off the branch tips where the caterpillars are feeding.
Drop the picked-off caterpillars into a can of soapy water to kill them and burn or otherwise destroy the pruned-off branches to stop the caterpillars from spreading.
In July, scout your plants for the scale-like egg masses and scrape or prune them off.
Cocoons can also be snipped off and destroyed to stop the insects from completing their life cycle.
Chemical controls If you have a lot of euonymus plants to take care of, or if the infestation is spreading too fast, you may wish to use a chemical control.
Several reduced-risk pesticides are available to control soft-bodied caterpillars that are less harmful to human health and the environment than the conventional stomach poisons.
These products include insecticidal soaps, dormant oils and pheromone traps.
Pesticides that contain a bacterium that is toxic to the pest, such as B.
t.
, are also considered safer for the environment.
Be sure to read the label carefully and follow all the directions and safety precautions.
After applying a pesticide, check the plants again a few days later to make sure the application was effective.
It may be necessary to retreat.
The key to effective control is to apply the pesticide in the spring while the larvae are still small and before they have done too much damage to the plant.
Follow-up Euonymus caterpillars first begin feeding at the tips of branches and then move inward to cover more and more of the plant with webbing.
The caterpillars are feeding inside the webs and, in some cases, completely defoliate the euonymus tree or shrub.
Euonymus may survive the first defoliation but eventually they will die if the defoliation continues each season.
Keep scouting and observing the health of your eunoymus plants.
Rake up and remove any debris around them to catch any cocoons that may have dropped to the ground.
Prune out any dead branches and keep your euonymus plants healthy by watering and mulching especially during hot weather.
Healthy plants can resist insects and diseases more effectively.
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