| Grasshoppers can damage zinnias. Grasshoppers are difficult to deter because they come in from neighboring fields and yard. A biological control disease organism, the protozoan Nosema locustae might work. Nosema locustae is most effective on young grasshoppers. This biological control will reduce grasshopper numbers over a few days or weeks, but, generally, it is a slow-acting disease that takes at least a year to affect grasshopper populations. N. locustae is available at many garden shops and nurseries and is sold under various trade names. Use this product strictly according to label instructions. Because adult grasshoppers are older and tougher than the nymphs, they are more difficult to control. |
