DAMAGE FROM THE LARKSPUR MIRID DETERS CATTLE GRAZING OF LARKSPUR

The larkspur mirid (Hopplomachus affiguratus) is host specific to tall larkspur (Delphinium barbeyi Huth), These insects suck cen solubles f rom leaves and reproductive racemes, causing flowers to abort and leav es to desiccate, Cattle generally prefer larkspur flowering heads, pod s, and leaves, and are frequently poisoned The objective of this exper iment was to determine if cattle would avoid eating mirid-damaged Lark spur, A 2-choice cafeteria feeding trial was conducted to determine pr eference for mirid-damaged and undamaged larkspur, Four cows were offe red a choice of the 2 types of larkspur in 10 min, feeding trials in t he morning and evening for 5 days, Cows preferred the undamaged larksp ur plants (0.8 kg +/- 0.08, SE) over mirid-damaged plants (0.1 kg +/- 0.03, SE), The cows were then turned out into a larkspur-infested past ure and consumption of mirid-damaged and undamaged larkspur was quanti fied by bite count, The cows did not select any mirid-damaged larkspur , Consumption of undamaged Larkspur peaked at 17% of bites on the seco nd day of the grazing trial, then declined as mirid damage on the plan ts increased, If the density of mirids on larkspur is sufficiently hig h to damage most of the leaves and flowering racemes, grazing by cattl e may be deterred, and subsequent poisoning avoided.