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Chart of Pests on Flowers

by Nanette Londeree, Master Rosarian

Let’s face it – for us rose lovers, it’s all about the blooms. It’s great if our plants are clothed in lush, emerald and ruby foliage, but it’s not why we grow America’s favorite flower. We want roses! And lots of them! It can be pretty frustrating to put all that effort into planting, feeding, watering, pruning and mulching, to end up with some wimpy blossoms, speckled with green wiggly little beasts, or big bold blooms riddled with holes. Just like us, there are lots of pests – big and small, that love rose blossoms. So, what’s bugging your flowers?

The majority of pests in the spring garden are insects. That’s not surprising, given they’re part of the largest and most successful animals on the planet – the arthropods. The arthropods include arachnids (spiders, mites and ticks), crustaceans (crabs, shrimp, pillbugs and sowbugs) and the immense group of insects. They make up over three quarters of all currently known living things with more than a million species identified and named - so far. Whether in the air, sea, on land (or in your garden), they’re incredibly successful creatures.

Getting to know the insects in your garden can aid you in your sleuthing when trying to figure out what might be damaging your flowers, or identify one of the good guys that you want to keep around. By knowing just a few things about these masters of the planet – their basic anatomy, how they eat and their lifecycle, you can quickly narrow down the possible nasty suspects, and, if you choose to treat them, develop an effective pest management strategy.

First – a bit of insect anatomy. Insects are animals with no backbone. To support their bodies, they have an exoskeleton, a skeleton on the outside rather than an internal one like ours. All mature insects have three pairs of jointed legs, one pair of antennae, compound eyes and up to two pairs of wings. The arachnids (spiders and mites) have two body parts, eight legs, no antennae, simple eyes and no wings. If you observe something crawling around in your rose blooms and you count eight legs, it’s not an insect – is an arachnid.

Stink Bug
Stink bug with piercing – sucking mouthparts

Another defining attribute of insects are their mouth parts – being aware of how they feed clues you in to the basic types of plant damage they cause. Insects that damage roses fall into three general categories. One group feeds by piercing and sucking (poking a hole in tissue and drawing out the plant fluid), aphids being a prime example. The group with rasping – sucking mouthparts scrape away plant tissue rather than pierce it. Thrips use this method and leave behind the telltale streaking and browning of petals. Both of these types of feeders excrete honeydew, a sweet liquid that supports the growth of sooty mold and attracts ants. Insects with chewing mouthparts produce the most obvious damage where they bite, rip or tear plant tissue. Beetles, caterpillars and leaf-cutting bees fall into this group.

Caterpillar with chewing mouthparts

The majority of insects undergo some type of metamorphosis (a change in form) during their lifetime. Many go through a simple one – egg, nymph and adult, where nymphs, the young stage of the insect, look like an adult only they’re smaller and lack wings.

Simple Metamorphosis

Aphids are a good example of a simple change in form; if you spot them on a rose, you may see many different sizes, as well as some shed “skins” – they shed their exoskeleton numerous times as they grow. For those that go through a complete metamorpho-sis, the change may be dramatic (think butterfly). These insects pass through four stages – egg, larvae, pupae and adult. And it’s usually the larvae of these insects that cause damage (caterpillars, rose slugs, etc).

Complete Metamorphosis

Armed with the knowledge of basic anatomy, feeding habits and lifecycle, how many different insects can you find in your garden? And, are they bugging your flowers, or helping keep the bad guys under control?

Photos of pests and damage (other than noted) courtesy of Baldo Villegas’ website at:
Photo of aphids and curculio damage by Nanette Londeree
Photo of phyllody by Bob Luttrell
Stink bug and caterpillar photos and metamorphosis lifecycles courtesy of Galveston County Master Gardener Association website at:

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Last Modified: 08/06/2013