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ground squirrelThere 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).

  • 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.
  • 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.
  • 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.
  • 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