Steamboat Springs Hoppers got the jump on many gardeners this year.
Although there are 80 kinds of grasshoppers in Colorado, most don't occur in large enough numbers to damage plants. However, when conditions are right, certain hopper populations do explode in 11-year cycles, lasting two to three years.
Right now, the clearwinged grasshopper (Camnula pellucidia) is the local horticultural horror story.
During outbreak periods such as we're experiencing this year in some parts of Steamboat, this pest species of grasshopper is the most destructive pest in our yards and gardens. They chew on grasses, leaves, flowers and stems of most every plant, often stripping them of all foliage, sometimes chewing completely through the stem and killing plants. If really hungry, they also chew on branches and leaves of trees and shrubs.
Unfortunately, once grasshoppers move into our gardens, our options for controlling them are limited. The large nematode (Mermis nigrescens) will kill or sterilize grasshoppers, as will blister beetles, robber flies and parasitic flies. Birds also eat this pest, particularly sage hens, hawks, kestrels and horned larks. But with millions of hoppers per acre, the smorgasbord is beyond their capacity to eat them all.
A microbial insecticide known by trade names as Semaspore or NoLo Bait is only effective against young grasshoppers. It contains a microsporidian called Nosema Locustae that is slow-acting and should be applied to the breeding areas outside your garden before the grasshoppers migrate into it. This product will take about two weeks to begin taking effect and must be purchased fresh and used right away. The young grasshoppers eat this bait and spread disease to other grasshoppers.
As grasshoppers come into your garden, insecticide treatments will have limited success because there is continual reinvasion by grasshoppers and the product wears off relatively quickly. Insecticides such as acephate (Orthene), carbaryl (Sevin), diazinon and malathion are available at local retailers. Please read and follow the directions carefully as these products are toxic to beneficial insects such as bees, flies and butterflies. They also leave residue on edible plants that can be harmful to humans. It's best to spray these insecticides at night or in the early morning when bees, flies and butterflies are less active.
Other steps you can take to manage the damage to your plants is to use floating row covers, till the dry, undisturbed areas where grasshoppers tend to lay eggs and even hand-pick grasshoppers in the morning when they are groggily resting on plants.
Some gardeners have found it effective to build a barrier strip of abundant green plants around the perimeter of their garden. Using insecticides in the barrier strip helps slow down the movement of grasshoppers into the garden.
Last year also, the grasshoppers were terrible out where we live west of town, so I'm hoping the cycle ends with this year. But, just in case, I'll be on the lookout for the young nymphs next May and June so I get the jump on hoppers before they get the jump on me.
Deb Babcock is a Routt County resident and a Master Gardener through the Colorado State University Cooperative Extension office in Routt County. No endorsement of products mentioned in this article is intended. Questions? Call 879-0825 or e-mail: firstname.lastname@example.org.