Field Guide for Integrated Pest Management in Hops

56A generalizedsummary ofthe seasonaldevelopmentand activity ofkey predatoryarthropodsincluding ladybeetles isillustrated inFigure 124,page 61.Seven-Spot Lady Beetle.AT RIGHT: Figure 107.Adult is relatively large(approximately 3/8 inch)and has a distinctive “1-4-2”pattern of black spots on thewing cases. (D. G. James)FAR RIGHT, TOP: Figure 108.Larvae are dark gray withorange spots. (R. Otten,Bugwood.org)FAR RIGHT, BOTTOM:Figure 109. Pupal stage lasts3 to 12 days. (D. G. James)Seven-Spot Lady BeetleCoccinella septempunctataDescriptionThis species is comparatively large(approximately 3/8 inch), with a white orpale spot on either side of the first sectionbetween the head and thorax (Fig. 107). Thebody is oval and domed. The spot patternis usually 1-4-2, black on the orange or redwing cases. Eggs are spindle-shaped andsmall, approximately 1/25 inch long. Larvaeare alligator-like, dark gray with orangespots on segments 1 and 4 (Fig. 108), andgrow to the same length as adults beforethey pupate (Fig 109).Biology and Life HistoryThis exotic species is a newcomer tohop yards, unknown before approximately2000. Currently, it is well established andoften as common and important as H.axyridis in controlling hop aphids. Adultsoverwinter in protected sites near fieldswhere they fed and reproduced the previousseason. In spring, emerging beetles feed onaphids before laying eggs. Females may lay200 to 1,000+ eggs during a period of oneto three months commencing in spring orearly summer. The spindle-shaped eggs areusually deposited near prey, in small clustersof 10 to 50 in protected sites on leaves andstems. Larvae grow from 1/25 to 3/8 inchin 10 to 30 days depending on the supply ofaphids. Older larvae may travel up to 36 feetin search of prey. The pupal stage lasts fromthree to 12 days depending on temperature.Adults are most abundant in mid- to latesummer and live for weeks or months,depending on availability of prey and timeof year. One to two generations occur beforeadults enter winter hibernation.Aphid-Feeding Lady BeetlesMonitoring, Importance in IPM and Compatibilitywith PesticidesAphid-eating lady beetles are extremely important to naturalsuppression of hop aphids. Growers should encourage the speciesdescribed here to colonize and reside in hop yards. Attraction andconservation of lady beetles is more effective and sustainable than thepurchase and introduction of H. convergens, which tend to rapidlyleave hop yards after released. Despite feeding primarily on aphids,these lady beetles also can feed on spider mites, thrips, and othersmall insects, and thus contribute generally to biological control.Lady beetles can be monitored by simply walking through yardsand conducting timed counts. Alternatively, they can be sampledby shaking foliage over a tray. A mean of one adult lady beetle everysecond or third plant represents a significant population capable ofresponding to aphid population increases. Lady beetles are compatiblewith many new, selective insecticides and miticides but are negativelyaffected by older, broad-spectrum pesticides.