Observations on the Alfalfa Weevil in Delaware, 19551

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Abstract
A small number of Hypera postica adult''s, kept in a container under outside conditions, failed to survive the 1954-55 winter. The few adults obtained from litter collections during the spring of 1955 indicated low winter survival, inadequate sampling technique, or little surface activity when samples were taken. Egg cavities in dead alfalfa stems ranged from 1 in 20 on March 10 to 1 in 6 on March 30, averaging 10.5 eggs per cavity. Spring-deposited eggs were not found until mid-March. Both egg production and hatching of overwintered eggs were retarded by low temperatures during the second half of March, which also greatly increased mortality of the embryonic stage and of newly-hatched larvae, and decreased viability of winter eggs. Hatching in the field began as early as March 16, and recently-hatched larvae were found in new alfalfa growth by March 23. The larval population peak, which was greater than in preceding seasons, was reached at or shortly after mid-May, later than in either 1953 or 1954. Although temperature conditions in March affect the rate of larval increase, there appears to be a more direct correlation between April temperatures and the time the first generation larval peak occurs. All attempts to recover Bathyplectes curculionis, introduced in 1954, were negative.

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