These excerpts are all from around 1980:

Northeast
The severe winters, short summers, and hilly or mountainous nature of the Northeast produce a variety of plants-but none which serves as a major source of nectar. Winter loss is usually high and is replaced with package bees and queens purchased from southern beekeepers. 

West
In the last few years, many beekeepers have had to replace almost 100 percent of their colonies due to pesticide losses. These losses are increasing each year. The major dollar loss to beekeeping in California is caused by (1) pesticides, (2) wax moth, and (3) foulbrood diseases.

Nye, W. P. 1980. Beekeeping Regions in the United States. Beekeeping in the U.S. USDA agric. Handbook. 335. pp. 10-15.

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In some parts of the U. S., bee losses to insecticides has been a chronic problem over the past 80 years (Atkins et al., 1970); but with the shift in recent years to insecticides with short residual activity but greater acute toxicity to bees, these losses have become widespread and often quite serious (Levin, 1970).

TUCKER, K. W., & Breeding, B. (1980). Tolerance to Carliaryl in Honey Bees Increased by Selection. American Bee Journal.  January.

* * *

The following shows what happened when DDT was banned and replaced by organophosphates. 

Two good examples of honey bee losses due to insecticide kills occurred in Arizona and California. In 1965 Arizona was almost totally dependent on the chlorinated insecticides and supported 114,000 colonies of bees. In 1971, with the change to organophosphate insecticides after the 1969 ban on DDT, the colony numbers dropped to 53,000 or a 50% loss. In that same period California was losing more than 80,000 colonies annually to pesticides, again due in great part to the shift from organochlorine to organophosphate insecticides.

Some sections of the United States have had particularly serious bee losses. As an example, the spraying of sweet com with sevin (carbaryl) for the control of oorn earworms was for several yr the main cause of an annual loss approaching 25% of commercial colonies in Washington state. Beekeepers now look upon pesticide poisoning as one of their most serious problems.

Ware, G. W. (1980). Effects of pesticides on nontarget organisms. In Residue reviews (pp. 173-201). Springer New York.

* * *

Killing of honey bees by insecticides has been a chronic, severe problem in Washington for at least 60 years (Melander 1920). A basic factor in this situation is the lack of sufficient wild pollen and nectar plants to sustain the number of colonies required for crop pollination. Most bees are pastured in the irrigated agricultural areas where they are subject to killing from insecticides. The 1980 farm value of bee-pollinated crops in Washington was $428 million. 

For many years, Washington beekeepers have been claiming a series of low to moderate level kills which seriously weaken their colonies during the summer. Such kills are hard to document because the dead bees ejected from the hives literally "dry up and blow away." Bee losses were greater during June and July than during August and September. This corresponds to the time of maximum insecticide usage. 

Mayer, D. F., & Johansen, C. A. (1983). Occurrence of honey bee (Hymenoptera: Apidae) poisoning in Eastern Washington. Environmental Entomology, 12(2), 317-320.

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