Hungry grasshoppers invade Roseville neighborhoods -- what to do

Hungry grasshoppers have overwhelmed Roseville, Lincoln and Rancho Cordova neighborhoods – and are looking for more to eat. As they mature, they become a lot more mobile; they can fly.

What’s a gardener to do?

Reports of the voracious grasshopper invasion started cropping up in early June as grasshopper nymphs chomped down on local landscapes. Some also invaded people’s homes.

Residents of Adelaide Drive, near Fiddyment Road in West Roseville, told ABC-10 that they couldn’t walk outside without seeing dozens of young grasshoppers, eating lawn and other plants. A Rancho Cordova resident interviewed by KCRA said she counted thousands in her backyard. Grasshopper infestations also have been reported in Butte and Tehama counties recently.

The Placer County Agricultural Commissioner called the invasion “unusual” – something that happens once a decade or so – and is working with cities, Placer County master gardeners and UC experts to tackle these pests.

Blame it on our spring weather. Short-horned grasshoppers (Melanoplus spp.) enjoyed perfect conditions for a population explosion: plenty of rain and warmth, then plenty of grass and weeds.

These grasshoppers breed in the grasslands, open fields and pastures that surround affected neighborhoods. According to officials, many more grasshopper eggs hatched and nymphs survived this season.

“In most years, these grasshoppers go unnoticed, but when conditions are favorable such as warm, moist springs when abundant food is produced, populations may increase dramatically,” says the Placer County ag commissioner in a statement. “Adult or nymphal grasshoppers may migrate into surrounding areas in search of more food.

“Severe outbreaks only occur every eight to 10 years and can last a couple of years,” adds the commissioner. “When wild food becomes depleted (i.e. grasses dry up in rangelands), grasshoppers migrate into neighborhoods and landscaped areas in search of food. Landscape plants can be a desirable food source for grasshoppers. Luckily, garden damage is usually limited to a few weeks in early summer, immediately after rangeland plants dry up.”

As the rangeland grasses browned in early June, the teen grasshoppers looked to lawns; they love lush grass. They’ll also chomp other green plants, right down to the stems.

Short-horned grasshoppers eat a wide range of plants, says the commissioner. “They prefer young green plants and enjoy consuming lettuce, beans, corn, carrots, onions, and some annual flowers. They dislike tomatoes and squash, so your tomato plants are safe unless there are no other food options nearby.”

When hungry enough, grasshoppers can chew through screens and come indoors in search of food. (They like pet kibble.)

Nymph grasshoppers molt (shed their skins) five times before they finally have wings and can fly. That usually takes about two months. That means the baby hoppers sighted in early June will be airborne by the end of July.

Here’s the real bad news: Short-horned grasshoppers can live two years and fly up to 10 miles. Expect more reports of grasshoppers over a much larger range.

Experts say this huge uptick in grasshoppers is likely to last two years (or more), depending on weather conditions.

Pesticides tend to be ineffective against these critters. (Birds usually control grasshopper populations.) The best defense is protection.

“Unfortunately, once large numbers of grasshoppers are present in residential landscaping, control options are very limited,” says the ag commissioner. “Individual plants may be protected by covering them with screens or cloth. However, grasshoppers will eat through cloth or plastic screen if hungry enough. Metal window screen is resistant to grasshopper mouthparts. A successful screening strategy could include screening your most desirable plants and leaving other plants available for grasshoppers to eat.

“Grasshopper populations may be reduced by manually removing insects through sweeping or raking and bagging for disposal. However, physical removal may not be effective for large grasshopper populations and will require ongoing removal to control.”

Wear gloves when dealing with grasshoppers. Dead grasshoppers stink, say Roseville residents, who compare them to dead fish.

Since they’re wingless, the nymphs are easier to catch (although they do hop!)