Texas Rice: What is this larvae?
As of May 2, according to the Texas Rice Crop Survey, 85, 75 and 1% of our Texas rice crop has been planted, has emerged and has been flooded, respectively. So, we are behind relative to past years due to cold wet weather during the early spring. However, April for the most part was cool and very dry.
At the Beaumont Center for April, we recorded less than 2 inches rainfall. Generally, dry conditions favor chinch bug populations and damage, but I have not observed much chinch bug damage this year.
I recently inspected a rice field in Liberty County and did see a few adult chinch bugs, but I don’t think they were damaging the rice to any extent. The farmer was preparing to flush the field which often drowns the insects and/or moves them up the plant where feeding causes much less damage compared to feeding at or below ground level. I also have observed some herbicide toxicity which I think results from cool weather slowing growth and metabolism of rice.
Poor Stand Culprits – What is this attacker?
In April, I was called out to a rice field to determine why the stand was poor. The field was planted in March and had endured exceptionally cold weather. The soil was clayey, had a lot of organic matter and had not been farmed in rice for years. I think seedling diseases were problematic, but we did find a few insect larvae attacking the germinating seed.
I know the larvae were not immature grape colaspis. I thought they may be wireworms, but upon closer inspection under the microscope, I tentatively identified them as rootworms. They are about 7/16 inch long (I think they are late instar larvae), are cream-colored, possess 6 thoracic legs, and have a brown head capsule and a brown terminal plate.
I have never observed these larvae attacking rice. About the same time, I inspected a grain sorghum field and observed the same type of larvae attacking the roots of seedling grain sorghum plants. Again, I was not familiar with these larvae, but they strongly resembled the larvae attacking germinating rice.
I plan to send the larvae to a corn rootworm entomologist for identification. Corn rootworm larvae are very serious pests in the Midwest. Here on the Gulf Coast of Texas, the adults of rootworms are very common in soybean fields.
The banded cucumber beetle and spotted cucumber beetle are the adults of rootworm larvae. The adults are foliage feeders and the larvae live underground and feed on the roots of their host plants.
I will keep you posted of further developments. I’m sure these larvae cannot survive a flood and maybe not a flush. I don’t want to alarm folks, because I don’t think this is a serious pest, but we need to be on the lookout for it. So, if you see larvae feeding on the roots of your rice plants before the flood, please contact me at 409-658-2186 or firstname.lastname@example.org.
I hope you join me in Costa Rica later this month for the Rice Market and Technology Convention—Pura Vida!