Conchuela Stink Bug in Texas High Plains Cotton: Identification, Injury, and Management

As we enter the boll formation phase of the crop, one insect pest I have been picking up quite consistently is the Conchuela stink bug. It is a relatively large insect (~1/2 inch long) with a distinctive dark olive green to black coloration and a reddish margin around the body. Their populations develop on mesquite trees and various weedy hosts, and as the quality of these host plants declines, they migrate into grain crops and cotton.

These stink bugs are voracious feeders and can be found in multiple numbers on the same boll (picture below). Stink bugs in general prefer to feed on medium-sized bolls, approximately the size of a quarter-dollar coin. Feeding on young bolls (<10 days old) often leads to boll shedding, while in larger bolls, stink bug feeding results in the formation of dark spots on the exterior. These dark spots do not always correspond to internal damage, which is why the newer stink bug thresholds are based on internal boll damage.

Dynamic boll injury threshold for stink bugs

If stink bugs are being detected along the field margin, I would consider spraying a couple of swaths around the field edges. This proactive approach can help prevent or reduce the spread across the entire field. Also, this way, the entire-field insecticide application can be better timed during the most vulnerable stages of the crop (3rd to 6th week into bloom) in case population build-up and/or reinfestation continues. We have had many situations in past seasons where stink bug infestations went undetected until damage became obvious late in the season. The only way to avoid this is through regular crop monitoring and timely insecticide application when needed.

The most effective insecticide products for stink bugs are either pyrethroids (e.g. bifenthrin, lambda-cyhalothrin) or organophosphates (e.g. acephate, Bidrin). These chemistries are much harsher on beneficials compared to some of the softer products used for aphids and plant bug control. Therefore, I would avoid rushing into an entire-field application unless stink bug numbers or internal boll injury justify the treatment. Neonicotinoids, such as imidacloprid can offer some level of stink bug suppression, but products commonly used for cotton fleahopper, aphid, or plant bug control (e.g. Carbine, Sivanto, or Transform) will not provide stink bug control.

Conchuela stink bug adults on cotton boll

South Plains Cotton Pest Update: Product Choices for Fleahoppers and Aphids

With some of the early-planted cotton already in the second or third week of squaring, we are starting to pick up quite a few cotton fleahoppers and isolated colonies of cotton aphids across the region. One of the common questions I’ve been getting is about product choices for managing these pests.

For cotton aphids, I would keep a close eye before pulling the trigger. With all the rain we've had over the past few days, there’s a good chance it may wash off some of the aphids. So, I would let the weather and beneficial insects work their magic before making a treatment decision.

Most of the products recommended for cotton fleahopper also have some activity against cotton aphids. For instance, Transform WG, Centric 40WG, and Carbine 50WG—all commonly used for cotton fleahopper control—also offer decent efficacy on aphids. Of these three, Transform has the best activity on cotton aphids and is also very effective against fleahoppers.

Some of the cheaper options include acephate and Bidrin 8. Acephate is the least expensive but also the least rainfast, with shorter residual activity. Bidrin offers slightly better rainfastness and longer residual control on both cotton fleahoppers and aphids; however, it is much harsher on beneficial insects compared to Transform, Centric, or Carbine.

Adult cotton fleahopper (picture: Pat Porter)

Plant terminal infested with cotton aphids