The control of strawberry-seed beetle (Harpalus rufipes Deg.); with observations on the damage it causes and that by linnets (Carduelis cannabina cannabina (L.))

In a laboratory trial, the previous diet of strawberry-seed beetles influenced their choice of food. The beetles generally preferred crushed oats to chicken pellets or bran though they fed more often on ripe strawberries than on the other foods. Baits of crushed oats containing malathion and fenitrothion (each at 0·15% active ingredient) and 0·1% a.i. of aldrin were eaten when strawberries were also available. In field trials, beetle mortality ranged from about 30% in small enclosed plots to about 90% in large field plots. Malathion bait remained effective for 5–7 days under wet conditions and 10–12 days under dry. Fenitrothion and aldrin baits were effective for 2–3 weeks. Observations made after using fenitrothion baits suggest that they are not a danger to wild life. In a survey of forty-seven commercial crops linnet damage was found in thirty-five crops and seed-beetle damage in three crops. Linnet damage was most severe in unstrawed maiden crops.