Insect Strip

Insect Strip

Friday, July 10, 2015

Update on Moth Trapping Captures

Two graphs are shown for each moth. One combines trap site moth captures by date to show the flight activity over time and the other graph shows the moth activity by each of the counties trap site. The County Extension Agent has information for trap site locations in a county. Some counties may not have been able to report their trap catches yet for a particular week. 
Southwestern corn borer

The graph with the county moth trap catches combined by date shows that the first moth flight peaked on June 22 and has declined to a few mothsby the July 6 sample date (Fig. 1). The graph showing weekly trap catches by a counties trap sites shows that Dallam, Deaf Smith, and Moore counties had the heaviest activity of southwestern moths (Fig. 2). Trap site 1 in Deaf Smith county had the most moths captured from June 9 to July 7.
Figure 1. Southwestern corn borers county moth captures by date.

Figure 2. Southwestern corn borers moth captures by county.


Fall Armyworm
Fall armyworm trap catches were highest on June 9 and have declined each week after (Fig. 3). Counties with the highest fall armyworm activity have been Hale, Moore, Ochiltee, Randall, and Swisher (Fig. 4). Parmer had difficulties setting up traps and was only able to report trap catches on June 30.

Figure. 3. Fall army worm county moth captures by date.


Figure 4. Fall army worm moth captures by county.


Western Bean Cutworm
Western bean cutworm (WBC) trap catches has increased every week with the highest numbers reported on July 6 (Fig. 5). The moth activity of WBC has been more wide spread across several counties this year. But, this last week there was higher activity in Dallam, Hartley and Moore counties (Fig. 6).
Figure. 5. Western bean cutworm county moth captures by date.

Figure 6. Western bean cutworm moth captures by county.



Sugarcane Aphid and the Yellow Sugarcane Aphid

Sugarcane Aphid Update

The latest news about the sugarcane aphid (SCA) is that on June 26 the aphids were confirmed by Dr. Charles Allen, Extension Entomologist, to be infesting grain sorghum fields in the West Central  area of the state. The field locations were 1 mile north of Coleman, another just west of Rowena in Runnels County, and a field in Tom Green County. Then on June 29, Dr. Pat Porter, Extension Entomologist, reported finding a colony of the SCA on Johnsongrass near the Lubbock airport. On, July 1, Dr. Allen reported finding dead blue sugarcane aphids mixed in with the normal colored aphids. These dead blue sugarcane aphids had been parasitized by an Aphelinus parasitoid wasp. And, on July 8, Tommy Doederlein, IPM Extension Agent for Dawson and Lynn Counties, found SCA in an overwintering cage infesting Johnsongrass. But, Blayne Reed, IPM Extension Agent for Swisher, Hale, and Floyd Counties, still does not have any SCA at his overwintering site in Hale County. No SCA have been found or confirmed to be infesting sorghum in the Southern High Plains or the Texas Panhandle. Still with the earlier detection of the SCA in Lubbock this year, Tommy Doederlein, Pat Porter, Blayne Reed, and Kerry Siders wrote an excellent article on the management of SCA in whorl stage sorghum. This article and more detailed information for the other reports are available on the Texas Sugarcane Aphid News on-line site (http://txscan.blogspot.com). Also, on this site is a video of an Aphelinus parasitoid wasp laying an egg in an immature SCA.
If you find or suspect SCA in sorghum fields, please contact Pat Porter, an IPM Extension Agent, County Extension Agent, or myself. The earlier we find and report SCA infestations, everyone in the High Plains will be better informed and ready if the SCA begin to infest grain and forage sorghums.

Photo: Scott Armstrong, USDA-ARS


Photo: Rick Grantham, Oklahoma State University

Yellow Sugarcane Aphid
While all of the attention has been on the new aphid, our yellow sugarcane aphid is showing up in grain sorghum fields. The County Extension Agent -Swisher, John Villalba, received a call on July 8 from a producer about finding aphids in his sorghum field. The farmer was concerned that the aphids were the new SCA pest. I was able to look at the aphids under a microscope and they were the yellow sugarcane aphid. It was important to properly identify the aphid so the correct control recommendations could be made.  The yellow sugarcane aphid, Sipha flava (Forbes), is usually a bright lemon yellow color with short spines (hairs) on the body. The cornicles (tail pipes) are very short and are barely seen without a hand lens.  The aphids feed on the underside of the lower leaves. When feeding the aphids saliva is toxic to the plant and causes seedling sorghum leaves to turn purple and older leaves to turn yellow. This toxin is very potent and very few aphids per leaf can cause a leaf to die. Economic injury levels have been established for yellow sugarcane aphids on seedling plants up to the three true-leaf stage (http://aglifesciences.tamu.edu/entomology/wp-content/uploads/sites/12/2014/07/B-1220.pdf). Larger sized plants can better tolerate more damage. Damage can still be significant on older plants, but we do not have a set threshold for making control decisions. However, using the same action threshold for greenbug on sorghum at different plant growth stages should prevent excessive yield losses when used for the yellow sugarcane aphid.

Action threshold levels for greenbug (yellow sugarcane aphid) on sorghum at different growth stages
Plant size
When to treat
Larger plant greater than 6 inches to boot
Colonies causing red spotting or yellowing of leaves and before any entire normal-sized leaves on 20% of plants are killed
Boot to heading
At death of one functional normal-sized leaf on 20% of plants
Head to hard dough
When colonies are sufficient to cause death of two normal-sized leaves on 20% of plants

There is very little data from research trials on products to use for control of the yellow sugarcane aphid. Our Extension guide, “Managing Insects and Mite Pests of Texas Sorghum”, lists dimethoate for use after sorghum has emerged. Some prefer to use a mixture of chlorpyrifos and dimethoate for yellow sugarcane aphid control.