The salivary secretions of some aphids are toxic and can cause severe tissue damage in the plant. Symptoms of aphid injury include leaf stippling, discoloration or striping. In addition, wilting, premature browning and death of the plants may result. Plant viruses also can be injected into the plants during aphid feeding. Disease can be transmitted whenever a low number of aphids move in or out of the field rapidly, making their presence difficult to detect.
Many aphid species undergo sexual reproduction and deposit eggs.
In the case of the greenbug, a female may produce two to three young per day under warm conditions, and females may mature in 7-10 days. This tremendous reproduction potential can result in rapid aphid population buildup. Males of some species are seldom if ever seen. No male Russian wheat aphids have ever been recorded in the United States, and male greenbugs are almost never seen in nature. Winged and wingless aphids may be present in the field.