Predatory Mirids: Campylomma verbasci (Meyer), Ceratocapsus pumilus (Uhler), Deraeocoris fasciolus Knight, Deraeocoris nebulosis Uhler, Deraeocoris nitenatus Knight, Hyaliodes vitripennis (Say), Hyaliodes harti Knight

I. Introduction: There are many predacious mirids active in deciduous fruit orchards in addition to those highlighted here. Species in the genera Pilophorus, Diaphnocoris; Blepharidopterus, Plagiognathus, and Phytocoris are particularly important control agents in some orchards in some years. Mirids (or plant bugs) are either plant feeding, predaceous, or a combination of both, and consequently are very important economically. This is particularly so where integrated (IPM), sustainable, biological control or organic systems of pest management are practiced. Most mirids are general rather than specific predators and provide predatory pressure on a broad range of pest species in an orchard but there are highly host specific exceptions. In economic terms it is generally agreed that the benefits of mirids feeding on the eggs, immature stages or even adults of many insect and mite pests far outweigh the damage done by plant feeding species. However, serious fruit and or foliage injury is sometimes attributable to a few plant feeding species such as Lygus lineolaris (Palisot de Beauvois) (tarnished plant bug) and Campylomma verbasci (mullein bug).

II. Hosts: The mirids mentioned (and many others) are all commonly found on apple and many may also be found on other deciduous fruits, bushes or trees. A few species feed on the fruit or plant tissues and others may cause injury by their ovipositional activity. Some species such as C. verbasci are predaceous on insects and also feed on and injure plants or fruit. The majority of species feed on one or several of the following; mites or mite eggs, insect eggs, small larvae or soft, easily subdued adults. Aphids of several species are hosts for many mirid species. Predation on other susceptible predatory arthropods is not uncommon.

III. Description: Each species is very distinct and only a general description of the family Miridae can be provided here. Illustrations are provided for Hyaliodes harti and H. vitripennis adults (Plate 137), H. harti nymph (Plate 138), Deraeocoris nebulosus adult (Plate 139) and nymph (Plate 140), D. nitenatus adult (Plate 141), and Ceratocapsus pumilus adult (Plate 142) and nymph (Plate 143). Adult Miridae collected on fruit crops are distinguished from the other bugs by four segmented antennae, the four segmented rostrum (beak), and the absence of ocelli (rudimentary eyes). The forewing has a hardened basal half and a membranous posterior portion. The abdomen consists of nine segments but only eight are visible.

Nymphal mirids are very tiny, delicate creatures which may not resemble the adults very much. However, with each successive molt the nymphs more closely resemble the adults of their species. Wings and genitals are lacking or rudimentary in the nymphal stages.

IV. Biology: Most mirids overwinter as eggs that are laid in soft plant tissue. The eggs are commonly completely imbedded, or have just the operculum (a round disk) exposed although sometimes the egg may be completely exposed on the leaf or plant surface. Nymphs of most species emerge in the spring at a time when there is sufficient new host plant growth or prey available on which to feed. Normally each nymph passes through five nymphal instars, each of five to seven days duration. Adults are voracious, continual feeders but males are short lived after mating. After oviposition the eggs require ten days to two weeks before hatching. Again the newly hatched nymphs pass through five instars and some overlap of the first generation adults (especially females), by the more numerous second generation does occur.

V. Injury: Terminal shoot growth of lateral branches as well as the central leader of the tree may be heavily fed on by C. verbasci nymphs or adults, commonly known as the mullein bug, with resulting tissue death and shoot stunting or distortion. Feeding by C. verbasci on the fruit itself gives rise to small, raised, reddish, pimple-like spots on the fruit surface. When numerous injuries occur on the same fruit it becomes twisted or distorted. This type of injury usually occurs when there are not sufficient numbers of mite or aphid prey to sustain the predatory population. Some fruit injury is caused by mirid oviposition but this type of injury is not significant.

from a chapter in the Mid-Atlantic Orchard Monitoring Guide (Northeast Regional Agicultural Engineering Service (NRAES) Publ. 75), entitled Mite Predators,
by L.A. Hull and R. L. Horsburgh

E-mail to: Douglas G. Pfeiffer