. Cooperative economic insect report. Beneficial insects; Insect pests. - 343 - SPOTTED ALFALFA APHID - CALIFORNIA - Density of population about same as last year in Imperial County. Light to medium in San Di- ego County desert area. Light to heavy in Riverside and San Bernardino Counties. Some control necessary in Merced County but infestation heav- ier than last year. Generally, development slower than last year but infestation apparently will be severe again. (Harper). ARIZONA - High numbers on alfalfa in Yuma area causing damage where insecticides not applied at least once a month. Populat
. Cooperative economic insect report. Beneficial insects; Insect pests. - 343 - SPOTTED ALFALFA APHID - CALIFORNIA - Density of population about same as last year in Imperial County. Light to medium in San Di- ego County desert area. Light to heavy in Riverside and San Bernardino Counties. Some control necessary in Merced County but infestation heav- ier than last year. Generally, development slower than last year but infestation apparently will be severe again. (Harper). ARIZONA - High numbers on alfalfa in Yuma area causing damage where insecticides not applied at least once a month. Populations also very high generally in Pima and Santa Cruz Counties in untreated fields. Winter infestations were lighter than last year and seedling treatments were not necessary or much lighter than in 1955. Populations now very high but total number of treatments should be less than last year. (Ariz. Coop. Rept., Car- ruth). IDAHO - No spotted alfalfa aphids found in a recent survey in fields infested in 1955 in Oneida and Franklin Counties. (Gittins). NEW MEXICO Build-ups following same pattern as spring of 1955 but more acres involved, Damage in isolated areas not having damage last year. In southern two- thirds of State with exception of Las Cruces area of Rio Grande Valley, infestations increasing. Damage severe on untreated alfalfa. Apparently due to weather, heavy infestations greatly reduced in Lea County, April 15. (Durkin). UTAH - Commonly present in unsprayed fields of Wash- ington County. (Knowlton). COLORADO - Early surveys in eastern and southeastern areas failed to show overwintering populations. This situa- tion existed in 1955, indicating possibility that severe winter temperatures may influence survival of this insect in Colorado. ⢠(Colo. Ins. Det. Comm. NEBRASKA - None found in Republican or Platte Valleys week ending April 21. (Andersen). KANSAS - Spreading northwest; now moderate to severe south of line from Bourbon County southwest through northern Sumner
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