Ground Squirrels

There are a wide variety of different species and subspecies of Ground Squirrel, but those of most concern to Agriculture and Crop Producers are California (Spermophilus beecheyi) and Richardson’s (S. richardii).

Identification

• There are 23 species and 119 subspecies of Ground Squirrels living in the U.S.
• 10” long, with a 6.5”, semi-bushy tail.
• Weight: 10-26 oz.
• Tall hairy ears, brownish gray hair & speckled.

Behavior

• All species of ground squirrels dig and burrow for shelter and safety.
• Burrow systems are occupied year after year and are often expanded each year.
• A number of squirrels often occupy the same burrow.
• Ground Squirrels escape to their burrows at night, during the warmest periods of summer days, and to escape predators.
• Ground Squirrels hibernate during the coldest part of winter.
• Hibernation ends in late February or early March.
• Males come out of hibernation 1-2 weeks before females.

Problems

• Ground Squirrels cause economic damage to food crops, golf courses and home gardens.
• They have been implicated in diseases spread to humans, notably the plague.
• Burrowing weakens levees, ditch banks, and undermines roadways and buildings.
• California Ground Squirrel has caused an estimated $30-$50 million of agricultural damage in California alone.
• Most serious native pest in California.

Reproduction

• Breeding begins shortly after emerging from hibernation.
• Gestation is generally 28-32 days.
• Litters yield up to 9 pups.
• Ground Squirrels have 1 litter per year.

Control Methods

• Exclusion
  • For many types of ground squirrels exclusion is impractical because they are able to burrow and climb over almost any type of structure.
• Trapping
  • Only works on small populations of ground squirrels and is difficult to do successfully.
• Fumigants
  • Only work well in small areas with infestations.
  • Only effective in compact and moist soils.
  • Expensive
• Poison Bait
  • ZP AG
    • Rodenticides are the most economical choice for ground squirrel control.
    • ZP AG is an acute product registered for use on ground squirrels.
    • Contains 2% Zinc Phosphide as the active ingredient.
    • Efficacy for ZP is improved dramatically with pre-baiting, but not necessary.
  • Restricted Use Pesticide – see product labels for complete application details & species

• PCQ Ag
  • .005% Diphacinone approved for control of California ground squirrels.
  • Approved for use in secured, tamper-resistant bait stations at ANY time of year for applications in: Vineyards, Fruit Tree Orchards, Avocados & Citrus Groves
  • Approved for Spot Baiting Applications during a non-bearing phase
  • Restricted Use Pesticide – see product labels for complete application details & species

• P.C.Q.
  • Special local needs label for use in California Only
  • Double strength Diphacinone at 0.01%
  • Controls Ground Squirrels using their natural foraging behavior.
  • Restricted Use Pesticide – see product labels for complete application details & species

Ground Squirrel Rotation