Field Guide for Integrated Pest Management in Hops

60Assassin BugsReduviidaeDescriptionAdults are blackish, brown, or reddishwith a long, narrow head; round, beadyeyes; and an extended, three-segmented,needle-like beak (Fig. 121). They are larger(2/5 to 4/5 inch) than other predatory bugs.Eggs are reddish-brown, skittle-shaped, laidin a raft of 10 to 25 or more, and coatedwith a sticky substance for protection (Fig.122). Nymphs are small versions of adults,although early instars are often ant-like.Figure 121. An adult assassin bug feeding on a beetle larva. Adult assassinbugs are relatively large (2/5 to 4/5 inch), blackish, brown, or reddish incolor, and have a long, narrow head and beak. (D. G. James)Biology and Life HistoryAssassin bugs are long-lived and consumelarge numbers of insects and mites duringtheir lifetime. Adults may live for morethan one season and nymphs are slow todevelop. Population densities of assassinbugs are usually low but they provide useful,consistent, and long-term feeding on aphidsand caterpillars in hop yards. They are mostfrequently found in yards with a groundcover. Populations of assassin bugs in hopyards in Oregon tend to be relatively low.Damsel BugsNabis spp.Figure 122. A raft of eggs laid by an assassin bug. Notice the reddish-browncolor, distinctive skittle shape, and clustering of eggs. (D. G. James)Predatory BugsMonitoring, Importance in IPM and Compatibilitywith PesticidesPredatory bugs are an important component of IPM, providingcontrol and suppression of spider mites, aphids, loopers, and thrips.They are particularly important early in the season, when predatorymites have not fully established, helping to suppress spider mitepopulations. They also exert significant control on aphid populations.The abundance of predatory bugs in hop yards is likely to increaseas broad-spectrum pesticide use decreases and greater use is made ofground covers. Monitoring of predatory bugs is best done by visualscanning of foliage or by taking canopy shake samples.DescriptionDamsel bugs are mostly yellowish,gray, or dull brown, slender insects up to½ inch long with an elongated head andlong antennae (Fig. 123). The front legsare enlarged for grasping prey. Cylindricalwhite eggs are deposited on leaf surfacesnear potential prey. Nymphs look like smalladults but are wingless.Biology and Life HistoryAdult damsel bugs overwinter inground cover, debris, and protected sites.They emerge from hibernation in Apriland soon begin laying eggs. Numerousoverlapping generations occur during theseason. Both adults and nymphs feed onsoft-bodied insects and mites includingaphids, loopers, spider mites, leafhoppers,small caterpillars, and thrips. A number ofdamsel bug species are seen in hop yards,particularly those with a ground cover.