In new England, the GPA is easily controlled by beneficial insects and other natural control agents throughout most of the season. Beneficials include both the immature and adult stages of various lady beetles species , minute pirate and damsel bugs, predacious midge, flower fly and lacewing larvae, several species of parasitic wasps, spiders and fungal pathogens. Applications of broad-spectrum insecticides kill many of these beneficials and allow aphid populations to increase rapidly. Aphids have tremendous reproductive capabilities and can quickly build to damaging levels if their populations are not contained by naturally occurring parasites and predators or other factors. Under warm conditions, each aphid can produce 80 or more young females in a week.
Many generations occur in a single season.
Once the beneficial insect complex is killed off, there is little change that they will regain control over the rapidly expanding aphid population. To further complicate the problem, both the GPA and MA are resistant to most insecticides. When applied, aphicidies usually result in less than adequate control, allow the aphid populations to continue to increase, and result in even more spraying. This strategy allows the beneficial insects to keep the aphids in check through most of the season until it is too late for them to cause significant economic damage. When pepper transplants come out of the greenhouse with as many as 50 GPA per leaf, if left unsprayed, beneficials in the field reduced the population to less than one aphid per leaf in as little as one or two weeks.