The Diagnostic Process Arthropods Associated with Turf and Ornamentals Carol Sutherland, Extension Entomologist The relationships among plants, Basic Features of An Adult Insect insects and their relatives are extraor- dinarily complex, even in garden and Let’s begin by reviewing basic features of a common landscape situations. Some gardeners adult insect and introducing the subjects of molting fear insects, consider nearly all of them and metamorphosis. A brief study of five different as “pests,” and overreact to their pres- kinds of mouthparts on insects will show different ence. Others are not aware of the stressful conditions ways that insects get their food, and, for pests, cause that may make plants more susceptible to serious specific kinds of damage to plants that you’re certain pests for which we have few or no controls. There is a to see. Finally, we’ll consider how insects are named happy medium. and categorized as a background for the general field guides that follow. In this section, you will learn enough about the devel- opment and classification of arthropods (that is, in- An adult insect, such as a grasshopper, has these com- sects and their jointed-leg relatives) that you’ll be able mon features: to identify many common species, as well as appreci- ate their roles in your yard and garden. This knowl- • three body regions (head, thorax, abdomen) edge should dispel fears, while bolstering confidence • three pairs of legs (one pair per segment on thorax; about your plant and pest management decisions. no walking legs on abdomen) While many species are described in the insect field • two pairs of wings (on 2nd and 3rd segments of tho- guides below, many more are not listed in the inter- rax) ests of space. As always, if you encounter unfamiliar • one pair antennae insects or their relatives, collect a sample and bring it • mouthparts chewing (or modified) to your county agent; then share what you learn. • an external skeleton fortified with chitin, which provides flexibility or strength. • paired compound eyes Basic Information on Insects and Their • bilateral symmetry (right side looks like a mirror Relatives (The Arthropods) image of the left) • appendages jointed and body segmented The arthropods include the “jointed foot” (arthro = • produced by molting from an immature stage jointed; pod = foot) animals, such as insects, mites, • does not molt again after it becomes adult ticks, spiders, all of their various relatives (millipedes, • adult can reproduce and disperse centipedes, scorpions, pseudoscorpions, pillbugs, sowbugs, shrimp, crabs, crayfish, lobsters), and their relatives. For purposes of this discussion, we’ll focus on those land-dwelling, air-breathing arthropods we consider pests of ornamentals and turf. Later, we’ll re- view some common species that attack some of these same arthropod pests. Some of these attackers might be considered beneficial because they help control pests, while others are too venomous or too inefficient to be encouraged in our gardens. Finally, there are some common garden and landscape inhabitants that are not arthropods. But since they will not be covered elsewhere in this manual, you’ll find them addressed here. Adult insect common features. NMSU Gardening Advisor I.A.1 New Mexico State University Gardening Advisor Molting • Simple Metamorphosis. The life cycle begins with the egg, proceeds through a series of progressively Having an external skeleton is a disadvantage for larger, more complex nymphs, ending in a winged insects and their relatives because it would appear (or wingless in some species) adult. Nymphs typi- to limit growth and development. The solution to cally look like smaller versions of adults and occupy this problem is molting or shedding the old skin and the same habitat and hosts as the adults. Nymphs expanding the new skin to a larger size. The new skin have compound eyes and external wing pads for can incorporate new, enlarged, or modified body winged species. parts, permitting new bodily functions or activities. Molting is a complicated process controlled by various hormones. Depending upon species, insects may molt several to many times as immatures. For insects, molt- ing ceases when they become adults. split in skin over thorax • Complete Metamorphosis. The life cycle begins with the egg, proceeds through a series of ever larger larvae, through a transitional stage, the pupa, molted linings of respiratory system and ends with the adult. Larvae look completely different from the corresponding adults with a few simple (single lens) eyes or no eyes at all and no ex- ternal evidence of wing development. While some species are legless, others can have legs that look Metamorphosis radically different from those in the corresponding adults. Larvae may occupy very different habitats Metamorphosis refers to the changes in form that ac- and use very different food sources from adults. company growth and maturation. We’ll consider three levels of metamorphosis here and in the field guides that follow: Mouthpart Types • No Metamorphosis. The life cycle proceeds from the egg through a succession of progressively larger, subtly changing nymphs, ending in wingless but reproductively active, crawling, or hopping adults. Springtails and silverfish are good examples. Mouthpart types permit different insect species to exploit their environments effectively and often competitively. They also are useful in arthropod identification and for explaining the type(s) of damage done by insects and their relatives. Com- mon mouthpart types include: • Chewing Mouth Parts. This is the most common mouthpart type. It may be found in immature I.A.2 The Diagnostic Process insects only or in both immatures and adults, de- left mandible is functional. Thrips feed by scraping pending upon species. Paired mandibles each have succulent plant tissue with the mandible and slurp- one segment and are jointed for side-to-side action. ing up the fluid-tissue slurry. Additional parts function as cheeks (maxillae), upper lips (labrum), tongue (hypopharynx), and • Siphoning Mouthparts. These are common lower lips (labium). These additional parts have among adult moths and butterflies. The long, flex- numerous sensory endings as well as muscles that ible, coiled proboscis is formed from two parts of permit insects to feel, smell, and taste their food as well as guide it into the jaws and mouth. A few examples include beetles, caterpillars, grasshoppers, termites, and earwigs. • Piercing-Sucking Mouthparts. The mandibles are elongated into paired needles that form two chan- Mandible Labrum Mandible Maxilla Labium the cheeks, and there is no special salivary channel. Liquids are sucked through the proboscis. Blood pressure uncoils the proboscis, while its own elas- ticity recoils it. nels for injecting saliva and ingesting liquid food. • Chewing-Lapping Mouthparts. Honeybees have Examples include aphids, whiteflies, stink bugs, these mouthparts. The mandibles are retained and squash bugs, and their relatives. a secondary tongue-like structure is formed from • Rasping-Sucking Mouthparts. These are unique to thrips. The right mandible is reduced, but the Cross-section of piercing-suck- ing mouthparts mandibles Siphon extended Siphon coiled I.A.3 New Mexico State University Gardening Advisor parts of the cheeks and lower lip. Bees lap nectar sterile at best. from flowers, chewing at blossoms as needed to expose the nectaries. When a systematic entomologist finds a different insect, he or she studies it, compares it with similar described species, and determines whether or not it Systematics should be described as a new species. The scientific name is the formal name for this new species. It con- sists of a genus (capitalized) and species (lowercase) name plus the author’s (describer’s) last name. The genus and species are either italicized or underlined. Many of these names have their roots in either Latin or Greek. The scientific name for this species will have the same meaning worldwide. You will see a few scientific names in the field guides below. Common names are more useful and understandable to gardeners and those will be favored if available. As the phrase indicates, these are common names for common creatures. They have little or no scientific mandible for chewing standing and may vary among different cultures or different areas of the world. tongue-like structure for lapping In the field guide that follows, insects and their relatives will be grouped by order and secondarily by family. The order is the most inclusive grouping. While the scientific names for the orders may be for- eign to you, the common names for them or common Entomologists estimate that there are as many as 30 examples will probably be familiar. One benefit of this million species of insects in the world. The majority type of organization is that if you find an insect new of these are known from the complex ecosystems of to you, you can probably sort it into the proper order the tropics, where conditions support a great diversity without much difficulty and at least narrow the pos- of animals, plants, and microorganisms. More than sibilities of what it is by reviewing common families 100,000 species of insects are known from North or examples included in that order. America. As on other continents (except Antarctica), they can be found practically everywhere in all sorts of roles. Some are specialists, while others are general- Field Guide to Pests of Turf and ists. Some feed only on plants, while other species are Ornamentals in New Mexico omnivores, and still others are predatory or parasitic. Systematics is a method of not only organizing and Terrestrial Snails and Slugs. These potential garden making sense of this great diversity of species, but also of setting up rules for naming and describing new spe- cies. The same rules and procedures also are used for studying, naming, and organizing other life forms. The basic unit of systematics is the species.