Brownheaded Ash Sawfly

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The brownheaded ash sawfly is a type of leaf feeding sawfly, which may look like a caterpillar or worm at first but is more like an ant or bee. It is a type of non-stinging wasp, but it goes through complete metamorphosis.

Lifecycle of the Brownheaded Ash Sawfly

The insect only goes through one generation a year, and will cocoon in the soil around the base of a tree during the winter. This tree has already been infested by the sawfly, so it makes sense to cocoon here.

Pupation happens in the early spring, with adults emerge by the end of April. They will then lay their eggs after mating, and the young larvae hatch from them before cocooning.

The larvae look a little like worms with their pale green coloring. When they transform into adults, they are small and black. They are technically wasps, but they don’t sting.

The Damage Caused by Brownheaded Ash Sawflies

The insect will cause damage during the larvae stage through the chewing of leaves. The damage isn’t usually too bad, unless there is a major outbreak. If there are a lot of them at one time, you’ll see that the trees become stressed and they struggle to grow more leaves.

The worms can become a nuisance as they start moving to their new sites for the winter, as well. They eat on the way, causing damage to these other sections. They also leave their papery larval skin behind. This remains attached to the leaves, but usually doesn’t cause any extra damage.

Handling the Brownheaded Ash Sawfly

One of the best natural defenses against the sawfly is a parasitic wasp. They will attack their prey and prevent an infestation from happening.
Mother Nature can also help. A late spring frost can cause the young larvae to die from the colder temperatures.

However, you will likely need a insecticide to tackle the overall problem. Carbaryl and permethrin are two of the best options, but you will need to use them as soon as you see an infestation is taking place.

SprayTech offer tree spraying, noxious weed control services, deep root watering and fertilizing services.