Dogwood Sawfly is an insect pest that can affect dogwood plants in summer. Sawflies are from the order Hymenoptera (same as ants, bees, and wasps). There are many types of sawflies, like the rose slug and hibiscus sawfly, and immatures feed on many common landscape plants.

Characteristics

Larvae have chewing mouthparts
Feed gregariously
Chewing behavior causes leaf damage
Have multiple larval stages before becoming a wasp-like adult

Mature dogwood sawfly larvae feeding on a leaf. Photo credits: Jerry A. Payne, USDA Agricultural Research Service, Bugwood.org.

Dogwood sawfly larvae on a leaf. Circled in red are the real legs, and circled in blue are the prolegs. Photo credits: Emma Giancola.

Figure 3: Dogwood sawfly larvae on an eaten leaf. Photo credits: Emma Giancola.

Dogwood sawflies can be managed using natural pest control methods, including natural predation, plant selection, plant maintenance, and monitoring the situation. There are also pesticide options available if the damage is out of control. The type and timing of pesticide applications are critical for success.

Life Cycle

One generation per year, between 1041-3914 GDD50
Adult female sawflies lay eggs on the underside of dogwood leaf
Uses a saw-like ovipositor (hence the name!)
Eggs appear as little dots near leaf veins.
Visible to the naked eye or with a hand lens- See Figure 4-- green and brown dots.
Freshly-hatched larvae appear small and caterpillar-like with a white, waxy coating- See Figures 2, 3, and 5
Larvae darken and become larger with age- See Figure 1

Types of Damage

"Windowpaning": Recently hatched larvae strip away outer layers of tissue- See damage northwest of larvae in Figure 5
Larvae eventually eat all parts of the leaf- See damage in Figures 1 and 3
Defoliation can weaken or kill plant

Figure 5: Dogwood sawfly larvae and larval damage on a leaf. Photo credits: Emma Giancola.

Figure 4: Dogwood sawfly eggs on a leaf. Photo credits: Emma Giancola.

How do I Control This?

1- Consider your options when planting

Dogwood sawfly somewhat prefers gray and yellow dogwood over flowering dogwood
Keep an eye on already planted dogwoods throughout the season, especially more remote specimens

2- Encourage natural predators

Arthropod predators, including wasps, spiders, and predatory stink bugs
Non-arthropod predators, including birds and lizards

3- Trim impacted areas

Safely dispose of any leaves and branches that have eggs or larvae present

4- Pesticides

Use when larvae are younger for maximum effect
Do not use Bacillus thuringiensis (aka B.t.)
Contact your local extension office for more specific pesticide recommendations.

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