Pepper maggot is closely related to apple maggot and has one generation per year. Because flies lay eggs directly into pepper fruit, the damage often goes unseen until it is too late. In the northeast, pepper maggot has typically been a pest in southern New England - Connecticut, southeastern Massachusetts, and scattered locations farther northward. It is often a farm-by-farm or field-by-field phenomenon without any clear reason for high or low populations that occur in a particular place.
The best way to detect pepper maggot activity is to look for stings on the fruit, which are easiest to spot on cherry peppers. Pepper maggot flies are smaller than a house fly, bright yellow with three yellow stripes on the thorax, with green eyes, and clear wings with a distinct banding pattern. On a daily basis, flies enter the field and return to the surrounding forest, passing across the border areas. Females insert their eggs directly into the pepper fruit and leave a small dimple – an oviposition sting or scar. The legless white maggots feed and tunnel inside the fruit, especially in the placenta. Maggots reach about ½ inch in length over a period of about two weeks, and have no distinct head capsule. When they are ready to pupate, they exit at the blossom end, leaving tiny round exit holes. These holes allow for the entry of pathogens into the fruit. Sometimes the oval brown pupae can be found inside the fruit. Often damage is detected only because of premature ripening or decay of the fruit.
Adults emerge in mid- to late July and actively lay eggs in pepper fruit for several weeks. Eggs hatch into maggots, which tunnel into the fruit, and then exit at the blossom end when they are ready to pupate. Pepper maggot pupates in the soil and overwinters as a pupae before emerging the following spring as an adult.
Monitoring & Thresholds:
Flies are attracted to bright yellow colors. Yellow sticky cards (3X5 inches) are inexpensive and easy to use; attach them with small wire stakes and place near the soil. Check and change traps twice weekly to record changes in fly ;activity (sources: Great Lakes IPM, Gemplers). If you suspect that you've captured a pepper maggot fly, check nearby fruit for oviposition scars.
Cherry peppers planted in border rows can work well as indicator plants, as they are the prefered pepper for pepper maggot flies. The egg-laying stings appear as depressions or scars and are easy to find on these small, round fruit. By timing insecticide applications with the first occurrence of the stings on the indicator plants’ fruit, damage to the main crop can be avoided with a minimum of spraying. If cherry peppers are not part of your crop mix, look for stings on bell peppers.
If this pest is a concern for your farm, consider using perimeter trap cropping. Plant one row of cherry peppers around the perimeter of the crop. These peppers are more attractive to the maggot flies than the sweet bells, so the flies will build up in the perimeter, allowing for a perimeter spray that will reduce pest populations and protect the main crop. Perimeter trap crop systems can be as effective as whole field sprays while drastically reducing pesticide costs.
If stings are observed on fruit, make two insecticide applications, 10-14 days apart, with a material labeled for pepper maggot.
Pepper maggot is usually a localized pest; many farms have never had a problem with this pest. Farms that have never had a problem with this pest generally do not need to be concerned; however, New England farmers should be aware that the range of this pest seems to be expanding.
For current information on production methods (including varieties, spacing, seeding, and fertility), weed, disease, and insect management, please visit the New England Vegetable Management Guide website.