Red head, dead to rights

The redheaded flea beetle, Systena frontalis, is a major insect pest in nursery production, skeletonizing leaves and making their host plants unmarketable. Adult beetles feed on many different ornamental plants. However, Itea sp., Hydrangea sp., Cornus sp., and Weigela sp., are some of the favored foods of redheaded flea beetle adults, making them particularly susceptible to damage. 

“Redheaded flea beetle has been a major issue in the Southeast and up and down the East Coast for years now and continues to be a problem,” says Jane Stanley, Green Solutions Team Specialist, Envu Turf & Ornamentals.

Though the pest is most problematic in the Southeast, it’s often seen east of the Mississippi, including states as far north as Ohio, New Jersey and even Connecticut.

It has spread, and it is native, for better or worse, Stanley says. There are flea beetles out West, she says, but not redheaded flea beetles.

Stanley says Envu has been involved in RHFB research and there is some promising new chemistry potentially in the pipeline, but the main factor in controlling and preventing the beetle is proper drench timing.

“It’s a tricky one for growers to balance logistically and from a labor standpoint, but it is a pest where the way that you treat it is even more important than what you’re treating it with,” she says. “If you can do a targeted drench application to that larval life stage you will get 80 to 90% control and then you can clean up any adults that may have escaped as opposed to targeting the adult life stage, where you’re never going to get the control that you need. They’ve already done the feeding damage. You’ve already got the aesthetic damage.”

Stanley recommends drench applications for nursery growers, which can be a tough pill to swallow if you don’t have the infrastructure for that.

“It could be a major labor sink,” she says. “So it’s a tough one, but the management strategy is there if you can embrace the drench application. There is a lot of chemistry that is very effective applied that way.”

However, proper timing is crucial. Growers need to apply the drench when the larva is there, but before the adults hatch. To time it correctly, they need to understand the pest’s life cycle.

Life cycle

Redheaded flea beetles overwinter as eggs in potting media. Creamy-white larvae hatch in spring, at around 250 degree-days (base 50°F), and begin feeding on roots. Adult redheaded flea beetles are small, shiny black, beetles with reddish to dark colored heads and long antennae. True to their name, they can jump great distances and do, when approached. Adults tend to emerge around 500 degree-days (base 50°F) from plants overwintered in structures and 900-1,000 degree days (base 50°F) if overwintered outdoors, although this can vary by year and region.

Growers can find an accurate growing degree day model for their area from their local extension office. Extension personnel can be valuable partners for growers.

This is the key to know when the redheaded flea beetle life cycle shifts. Stanley recommends Danny Lauderdale’s growing degree day publications. Lauderdale is the eastern region area specialized agent for nursery and greenhouse with NC State Extension. For more details on his research, reach him at dmlauder@ncsu.edu.

Many extension services send out updates based on growing degree day (GDD) data. Lauderdale does that for many counties and helps nursery owners and managers use the growing degree day model. He explains what you may be seeing at a certain number.

“Those resources can be very helpful for growers,” Stanley says. “They don’t have to track it themselves if they can plug into their extension resources.”

Photos courtesy of Danny Lauderdale and brett ortler

Management tips

Once growers are following growing degree days in their area based on the closest weather station or recording and calculating on site, Lauderdale recommends keeping a list of plant bloom at the nursery based on GDD base 50°F. This will guide scouting for first generation larvae and adults.

Scouting and keeping records will help determine application timing. Here are some application timing suggestions from Lauderdale:

1. Target pre-egg hatch with neonicotinoids, azadirachtin or cyantraniliprole. Neonicotinoids provide the best control of larvae and adults and the longest protection from foliar injury if applied to rooted cuttings or liners prior to potting. They can also be incorporated in potting substrate or applied as a drench or topdress after potting.

2. After egg hatch, target larvae with products like acephate, chlorpyrifos, Isaria fumosorosea or beneficial nematodes (Steinernema carpocapsae).

3. Make applications of adult foliar insecticides just prior to historical first-generation adult emergence or based on scouting susceptible crops closely and frequently.

Many foliar insecticides kill adults short term but don’t break the life cycle. Repeat applications are needed during the summer to control newly emerging adults. Make sure to follow label instructions related to rate and limited number of applications per acre and/or year, growing season or generation of insect. Use a rotation of products based on their IRAC (Insect Resistance Action Committee) classification to avoid resistance.