Why you need a mixture of two endoparasitic wasps including Aphidius colemani and Aphidius ervi. they can reduce the crop damage by parasitizing and killing a mixed population of a variety of host species of aphids that are responsible for the crop damage.
In the major cities of the Midwest and Northeast, they found relatively high paying jobs in meatpacking plants, shipyards, and steel mills. The second significant cause of the Great Migration was the desire of black Southerners to escape segregation, known euphemistically as Jim Crow.
They came to the United States for a variety of reasons, most notably because of the persecution, discrimination, fear, and economic problems they faced in Russia. 2 1/2 million of the 8 million immigrants who immigrated to America between 1880-1914 from Russia and Austria-Hungary were Jews.