Managing grasshoppers
Advances in knowledge of both grasshoppers and grazing strategies offer new hope for reducing grasshopper outbreaks.
“Grazing strategies that improve range condition are likely to reduce populations of the kinds of grasshoppers that are our worst pests,” said Jerry Onsager, an entomologist with the U.S. department of agriculture. “It’s a win-win situation for producers.”
Onsager said experiments and computer modeling allow researchers to anticipate some ways grasshoppers respond to grazing.
Hot dry weather prompts fast grasshopper reproduction. When shade given by grass is reduced, temperatures increase and humidity decreases, reducing grasshopper diseases. The heat accelerates egg development, growth of grasshoppers and egg production.
Read Also
VIDEO: Green Lightning and Nytro Ag win sustainability innovation award
Nytro Ag Corp and Green Lightning recieved an innovation award at Ag in Motion 2025 for the Green Lightning Nitrogen Machine, which converts atmospheric nitrogen into a plant-usable form.
“This suggests that any range management strategy that increases the amount of forage and shading of the soil should reduce the likelihood of future grasshopper problems,” Onsager said. “Deferred grazing and rotating grazing can be used to manipulate the time, rate and degree of defoliation.”
Onsager cited two examples of systems on working ranches that seem to be suppressing the pests.
The first is in eastern Montana. Rancher Ray Banister uses short high-intensity grazing at infrequent intervals. This forces cattle to eat unpalatable forage, which is about as nutritious as palatable forage, said Onsager. Banister rests sites for up to 23 months so forage recovers, seeds are produced and seedlings established.
The second example is in western North Dakota along the Little Missouri National Grassland near Watford City. Rancher Dale Greenwood uses a twice-over rotational grazing system developed specifically for the northern Great Plains by Lee Manske, a range scientist at North Dakota’s agricultural experiment station.
Manske advocates grazing at specific times chosen to stimulate grass to put out more tillers and a denser canopy. This takes advantage of the greater canopy of leaves and a rotational grazing schedule that stimulates pastures at different times in different years. By never treating the range in the same way in consecutive years, the same grasshopper species is never favored two years in a row.
“Grasshopper populations don’t explode all in one year,” said Onsager. “They typically double from year to year. If we can break one or two doubling cycles, we delay the peak numbers. This may delay the peak until normal weather changes drive grasshopper populations down again. This way you may be able to avoid the peak altogether.”
Though Banister’s grasshopper populations were not studied scientifically, his infestations of migratory grasshoppers remained low. Populations on the Greenwood ranch were sampled weekly in 1993.
On twice-grazed land, the number of nymphs began at 4.5 per sq. metre. On a nearby site grazed all season, nymphs were 21.42 per sq. m. Nymphs on the twice-over grazed land took over 36 days to develop compared to 26 days on the season-long grazed site.
Onsager said he is confident ranchers can use rotation or deferred grazing systems to manage grasshoppers.
– Montana State University
Colostrum saves lambs
Inadequate colostrum intake, leading to hypothermia and infectious diseases, causes up to 500,000 lamb deaths in Britain each year.
Well-fed mature ewes should produce enough colostrum for twin lambs, but poorly fed ewes may fail to yield enough for a single lamb.
In some mothers, colostrum secretion could be delayed beyond the first critical hours after lambing, said Linda Mitchell, research specialist with the Scottish Agricultural Colleges.
A lamb’s first suck immediately boosts its ability to generate body heat. A lamb born outdoors needs slightly more colostrum that one born indoors.
Early colostrum intake is essential for passive immunity as colostrum immunoglobulin content and lambs’ ability to absorb proteins declines rapidly from about six hours after being born. If the ewe’s ability to produce colo-strum or the newborn’s ability to obtain it are impaired, supplements are vital to keep lambs alive and healthy.
Mitchell’s advice is to take colostrum from another ewe lambing in the same environment and exposed to the same potentially infectious agents. Aborted ewes should not be used and if suitable ewes are not available, cow colostrum or a manufactured replacer could be substituted.
Cow colostrum is less concentrated than that from ewes, so the dose must be 30 percent higher. Anemia can be a risk, so mixing colostrum from several cows is advised. Cow colostrum has seven to eight percent fat compared with 28-30 percent in sheep colostrum.
Supplementary colostrum should be fed to lambs by stomach tube, allowing 50 millilitres per kilogram of body weight per feed.
– British Farming News
