Plant Bugs, Family Miridae

As their name suggests, most plant bugs feed on plants. Spend a few minutes examining any plant in your garden, and there's a good chance you'll find a plant bug on it. The family Miridae is the largest family in the entire order Hemiptera.

Description

In a group as large as the family Miridae, there is a lot of variation. Plant bugs range in size from a tiny 1.5 mm to a respectable 15 mm long, for example. Most measure within the 4-10 mm range. They vary quite a bit in color, too, with some sporting dull camouflage and others wearing bright aposematic shades.

Still, as members of the same family, plant bugs share some common morphological traits: four-segmented antennae, four-segmented labium, three-segmented tarsi (in most species), and a lack of ocelli.

The wings are a key defining characteristic of the Miridae. Not all plant bugs have fully formed wings as adults, but those that do have two pairs of wings that lie flat across the back and overlap at rest. Plant bugs have a wedge-shaped section (called the cuneus) at the end of the thick, leathery part of the forewings.

Classification

Kingdom – Animalia
Phylum – Arthropoda
Class – Insecta
Order – Hemiptera
Family – Miridae

Diet

The majority of plant bugs feed on plants. Some species specialize on eating a particular kind of plant, while others feed generally on a variety of host plants. Plant bugs tend to prefer eating the nitrogen-rich parts of the host plant – the seeds, pollen, buds, or emerging new leaves – rather than the vascular tissue.

Some plant bugs prey on other plant-eating insects, and a few are scavengers. Predaceous plant bugs may specialize on a certain insect (a particular scale insect, for example).

Life Cycle

Like all true bugs, plant bugs undergo simple metamorphosis with just three life stages: egg, nymph, and adult. Mirid eggs are often white or cream-colored, and generally long and thin in shape. In most species, the female plant bug inserts the egg into the stem or leaf of the host plant (usually singly but sometimes in small clusters). The plant bug nymph looks similar to the adult, although it lacks functional wings and reproductive structures.

Special Adaptations and Defenses

Some plant bugs exhibit myrmecomorphy, a resemblance to ants that may help them avoid predation. In these groups, the Mirid has a notably rounded head, well distinguished from the narrow pronotum, and the forewings are constricted at the base to mimic an ant's narrow waist.

Range and Distribution

The family Miridae already numbers well over 10,000 species worldwide, but thousands more may still be undescribed or undiscovered. Nearly 2,000 known species inhabit North America alone.

Sources

• _{Borror and DeLong's Introduction to the Study of Insects, 7th edition, by Charles A. Triplehorn and Norman F. Johnson.}
• _{Encyclopedia of Entomology, 2nd edition, edited by John L. Capinera.}
• _{Biology of the Plant Bugs (Hemiptera: Miridae): Pests, Predators, Opportunists, by Alfred G. Wheeler and Sir Richard E. Southwood.}
• _{Family Miridae, Plant Bugs, Bugguide.net, accessed December 2, 2013.}