Family Miridae – Plant Bugs

The Miridae are unique within the Heteroptera in their possession of specialized setae known as trichobothria on the middle and hind femora. Most species lack the pair of ocelli found situated between the compound eyes of the majority of heteropteran species; the exception to this rule is the subfamily Isometopinae, which is thought to be the sister group of all remaining Miridae (the most basal lineage). The hemelytra, or forewings, nearly always have a well-demarcated cuneus, a triangular structure that is found in some other groups such as the non-parasitic Cimicoidea (bed bugs and their relatives) and whose anterior margin if formed by the costal fracture.

The pretarsus (claws and associated structures) shows much greater variation in the Miridae than in most other hemipterans, and provides many features crucial for understanding the subfamily classification of the group. As in most other bugs, the claws in the Miridae are symmetrical, the right and left claws being similarly developed. They may bear a pulvillus, a fleshy pad, on the ventral or interior surface of the claw; the exterior claw surface is sometimes ornamented with a few claw hairs of variable length. Between the claws are found the parempodia, paired, structures that arise from the distal end of the unquitractor plate. The parempodia are frequently in the form of common setae and are symmetrically developed.  Also present in some Miridae are structures known as pseudopulvilli that arise from the base of the claws. In some groups the pseudopulvilli have the appearance of parempodia whereas in others they look more like pulvilli. [1]

Plant bugs are economically and globally important pests of alfalfa, apple, cocoa, cotton, sorghum, and tea, among many other crops. Some plant bugs are predators of other insect crop pests and have been used successfully in biological control. Certain omnivorous plant bugs have been considered both harmful pests and beneficial natural enemies of pests on the same crop, depending on environmental conditions or the perspective of an observer.

As high-yielding crop varieties that lack pest resistance are planted, mirids are likely to become even more important pests. They also threaten crops as insecticide resistance in the family increases, and as the spread of transgenic crops alters their populations. Predatory mirids are increasingly used as biocontrol agents, especially of greenhouse pests such as thrips and whiteflies. [3]

Rhopalidae, the so-called "scentless" plant bugs is a much smaller family, with only about 200 species in 18 genera worldwide. However, the boxelder bug falls into this family, along with other agriculture pests (feeding as they do on seeds).