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Common Rose Pests - Part 5: Caterpillars and Sawflies

© Mark Whitelaw

I absolutely love butterflies and moths in the garden. I even plant perennials and annuals specifically to attract their presence. But I do not want their "kids" eating my roses! This week we take a look at Caterpillars and a critter that looks very similar, the larva of a Sawfly called a Rose Slug.

Caterpillars

Description: Like the pest beetles, these rose pests vary in size and description as well as genera and species. And like the beetles, their larvae have one thing in common: they love to eat the leaves of your landscape ornamentals.

Biology: Lifecycles vary. In general, the female lays eggs on the surface of desired plants and the eggs hatch into larvae we call caterpillars. Eventually, the caterpillars pupate, metamorphosis occurs and the adult emerges to begin a new cycle.

Damage: Caterpillars attack both leaves and blossoms leaving large holes with irregular shapes. The leaf rolling species wrap themselves in the foliage.

Control: There are numerous controls of these pests. From "least toxic" to "most toxic" these include:

1. Hand removal - Some species can be found only at night, meaning you may want to warn the neighbors about any potential strange-looking "flashlight roundups" in your garden. :>) They may be disposed to your backyard birds for feeding their young. Place the live caterpillars in a shallow cardboard box or screen-bottomed, platform feeder. Don't worry about them crawling out of the box. They won't remain there for long.

2. Row Covers - exclude the adult; although possibly a bit extreme for the average home gardener, their use by the commercial grower or for special occasions when protected shrubs are a requirement may be an option.

3. Companion planting - the blooms of Passion Vine (Passiflora sp.) are especially attractive to butterflies and moths. Adults choose to lay their eggs in this vigorous grower rather than my prized roses. The vine quickly recovers from any damage and the roses, planted a scant 2 ft. away, are left unharmed. Cornflower and Purple Coneflower are also reputed to be a "preferred attractors."

4. Permitting "social" wasps to make nests in the landscape and near the garden - species such as the paper wasps and mud dobbers will control caterpillars. Use caution if permitting them to build nests in well-traveled locations.

5. Inoculation with natural controls which include

a Parasitic Trichogramma sp micro-miniature wasp, which attacks the eggs before the caterpillars have a chance to hatch;

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