Understanding the locust life cycle can help explain why locust populations are so high and why controlling them can be difficult.
Grasshopper embryos begin developing in the eggs as soon as they are laid by the adults, and they must reach a certain stage of development before they enter a period of diapause (torpor) in the winter. What promotes the normal development of these embryos? Heat. These eggs need to accumulate heat by fall in order to hatch normally the following spring.
Grasshopper eggs need snow and vegetation to survive the winter, which protects and insulates the eggs laid in the upper layer of the soil. In the spring, more heat units are needed to complete development, but in the fall of the previous year, more heat units are needed. The eggs hatch and emerge as very tiny grasshopper-like larvae, which molt several times in a process of incomplete metamorphosis before reaching their final adult size.
Temperature also drives grasshopper feeding behavior: if temperatures are between 81 and 90 degrees Fahrenheit, grasshoppers will eat until they are full. They will then digest their meal by “pottering” until they are ready to eat again. If temperatures exceed 90 degrees Fahrenheit, grasshoppers will seek out shade or “stilt” – stretching their legs to lift their bodies off the warm soil. If temperatures fall below 68 degrees Fahrenheit or there is rain or wind, grasshoppers will stop feeding and seek shelter.
The fall of 2023 was one of the 10 warmest on record for El Paso County. It was followed by a warm, wet winter. Colorado experienced warmer than average March, April, and May with average moisture content. These factors are ideal for grasshopper egg growth and development. June experienced above average high temperatures in the ideal range for grasshoppers to feed during their vulnerable early growth stages after hatching.
What can you do to protect your garden? Right now, grasshoppers are in their late molting stage and insecticides are less effective. You can use traps, such as the homemade molasses traps recommended by Arizona State University Extension (https://cales.arizona.edu/cochise/mg/whats-bugging-you-grasshopper?utm_source=marketingcloud&utm_medium=email)
Remember that dead grasshoppers need to be removed regularly. If you have backyard chickens, you can let them roam in the yard under supervision in the morning when temperatures are cooler and the grasshoppers are less active. You can also cover valuable plants in your yard with insect netting, but grasshoppers may eat through the netting.
Plan now what you will do in the fall to prevent eggs from overwintering. You can till the soil after your final garden harvest to expose the eggs to the elements. Remove weeds around the garden that will prevent eggs from overwintering. In the spring, be thorough with weeding to reduce early season feeding, reduce hiding places for newly hatched larvae, and consider mulching to reduce the number of larvae that reach the soil surface.
Send your gardening questions to csumg2@elpasoco.com or call 719-520-7684. Our in-person help desk is open Mondays and Wednesdays from 9am to noon and 1pm to 4pm at 17 N. Spruce St. Find us on Facebook at Colorado Master Gardeners – El Paso County.
Send your gardening questions to csumg2@elpasoco.com or call 719-520-7684. Our in-person help desk is open Mondays and Wednesdays from 9am to noon and 1pm to 4pm at 17 N. Spruce St. Find us on Facebook at Colorado Master Gardeners – El Paso County.
