USU Extension

Identifying Insects in the Garden Landscape

By Nick Volesky, USU Extension

The earth is home to over one million different species of insects, with new species being discovered every year. Of these, less than one percent are considered pests to horticultural crops and landscape plants. Being able to identify different insects, their food preferences, roles in the ecosystem, and life cycles is an important skill for gardeners. Often, we focus on species that negatively impact our plants, but we forget to appreciate those with positive effects, such as through pollination, decomposition, or predation of harmful insects. Insects also play a vital role in the larger food web, providing a food source for vertebrates such as birds, mammals, and reptiles.

Familiarity with insect identification can benefit our management decisions, allowing us to manage specific species in ways that are cost-efficient and have minimal impact on the surrounding environment.

Like all living things, insects can be classified very broadly into large taxonomic groups down to specific species. This classification starts with the highest classification, the animal kingdom, followed by the phylum Arthropoda, which includes other arthropods like spiders, mites, and centipedes in addition to insects. The next taxonomic levels are class and order, which group insects that share common traits. Academics generally recognize 26-30 different orders of insects, with common ones including Lepidoptera (moths and butterflies), Coleoptera (beetles), Diptera (flies), Hemiptera (aphids, stink bugs, etc.), and Orthoptera (grasshoppers and crickets). The next taxonomic levels are families and genera. Within these groups, specific species of insects are categorized structurally or phylogenetically. For example, two types of grasshoppers are their own specific species but can be closely related enough to be within the same genus and family.

When looking for insects in the landscape, it is important to regularly check all parts of the plant from the seedling stage to maturity. This includes the foliage, flowers, fruit, stems, crown, and roots. When specifically looking for pest insects, you should watch for signs and symptoms. Signs are physical evidence of a pest, such as excrement (frass), shed skin, or the presence of the insect itself. Symptoms are the plant's reactions to a pest, which can include feeding damage, discoloration, wilting, or lesions. Helpful tools for gardeners include a beating sheet or tray, over which foliage can be shaken to catch any fallen insects for easier identification. A hand lens or magnifying glass can be used to see smaller insects more clearly.

For home gardeners new to insect identification, there are several resources available.

Sharing a photo on social media groups like The Utah Society of Entomology can pool identification suggestions and insights from other local naturalists. The Utah Plant Pest Diagnostic Lab accepts photos texted to 385-367-3773 and can provide free identification from USU Extension insect diagnosticians. Guidebooks like Vegetable Pests of Utah and Beneficial Insects of Utah provide references to several common species found within Utah, with photos and descriptions.