Cereal leaf beetle – larva Alberta Agriculture and Rural Development
Hosts
Oats, barley, wheat (preferred), corn, triticale, reed canarygrass, ryegrass, rye, fescue, other grasses (brome, orchard, foxtail, blue, timothy, quack), wild oats, and millet.
Identification
ADULTS: 6–8 mm long with reddish legs and thorax between metallic blue head and elytra.
Beetle, cereal leaf
MATURE LARVAE: 4–5 mm long, hump-backed body covered in slimy faecal material.
Oulema melanopus (Linnaeus)
Coleoptera
Life Cycle
Jan
Feb
Mar
Overwintering
Apr Eggs
May
June
Larvae
July
Aug
Pupae
Sept
Oct
Teneral Adults
Nov
Dec Adults
Adults overwinter outside fields under plant material, tree bark, building siding, and other protected sites. Each female lays 50 to 275 yellowish orange oval eggs singly or in batches of 3–4 touching end to end on the upper surface of leaves. Larvae feed for 2–3 weeks then drop to the ground to pupate in earthen cells for about 3 weeks. New adults feed for 2–3 weeks before seeking overwintering sites. One generation per year.
Feeding Damage
Overwintering Adults
Eggs Larvae
ADULTS: Feed on upper tissue between veins, causing uniform longitudinal incisions, but little if any economic injury. Pupae Teneral Adults
Jan . Feb . Mar . Apr . May . June . July . Aug . Sept . Oct . Nov . Dec
LARVAE: Feed on the upper surface leaf tissue causing elongated window pane-like damage. The rate of feeding damage increases as larvae mature. Yield quality and quantity is decreased if the flag leaf is stripped. Severely damaged crops have frosted appearance.
Cereal leaf beetle – adult Boris Loboda
Cereal leaf beetle – damage
Similar Species
Collops spp. are similar in appearance and size. These beneficial insects have a dark elytra often with orange to reddish thorax; elytra also have hairs which are absent in the cereal leaf beetle. The first segment of first 2 pairs of legs and the basal segment of the antennae are also reddish in colour. The leaf beetle, Gastrophysa polygoni (Linnaeus), also resembles the cereal leaf. It measures about 5 mm long and is green-blue in colour with an orange thorax and metallic green elytra.
Monitoring/Scouting
Beginning just before the boot stage, examine 10–20 plants at 5 sites following a “W” pattern across the crop, beginning from a field margin. Calculate the average number of larvae and eggs/ plant for the crop.
Economic Threshold
Pre-boot stage: 3 eggs and larvae or more per plant, including all the tillers present before flag leaf emergence. At the boot stage: 1 larvae or more per flag leaf.
Management Options
BIOLOGICAL: The introduced larval parasitoid, Tetrastichus julis (Walker) (p. 134), has successfully reduced and maintained populations below economic levels. Lady beetles also feed on larvae. Dissect mature larvae for the presence of small yellowish parasite larvae to determine if T. julis is present. CULTURAL: Optimize crop development (nutrition management) to reduce impact of larval feeding. CHEMICAL: Apply recommended products if warranted. If T. julis found, leave up to 1 acre unsprayed in one or two corners adjacent to a shelterbelt and/or water body to allow the parasitoid to multiply.
Bob Hammon, Colorado State University, Bugwood.org
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Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and Management Field Guide
Field Crop and Forage Pests and their Natural Enemies in Western Canada IDENTIFICATION AND MANAGEMENT FIELD GUIDE
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