With the relatively warm winter this year, it seems that the grub season is also starting a bit early, and we had reports from 3 customers that found grubs while they were digging in their flower beds. We didn’t notice any turf damage or armadillo holes yet, but these are certain to follow soon after.
White grubs are larvae of various scarab beetles. They stay in the ground (usually 2-6 inches deep) and feed on the roots of warm and cool season grasses. Healthy turfgrass that is not under stress can usually tolerate 6-10 grub per square foot, but since many lawns in the Austin area have been damaged due to last year’s watering restrictions, any additional stress to the turf is not recommended.
Identifying grub activity can be difficult, especially on lawns already damaged or stressed by improper irrigation; three methods we use:
Armadillo tracks on morning dew, and armadillo holes in the lawn. Armadillos love eating grubs, and this is the easiest sign to spot and notify you that you have a grub problem.
Weak and dying patches of turf which are slowly expanding. Dig on the border of the patch to confirm grub activity.
Digging 1 square foot patches of turf to check for grub activity. This is most invasive and time consuming, and we generally don’t recommend it.
While preventative grub control is possible, it must be timed correctly, and applied in the summer to control newly hatched grubs. These products will not control large grubs present in the spring. Most of the products in big box stores are of this nature (active ingredient is most often imidacloprid).
For curative (contact) control for grubs we find in spring, only carbaryl and trichlorfon are effective. We have found that Anderson’s DuoCide (carbaryl and bifenthrin mix) at high rates (8 lbs / 1,000 sqft) gives us the best results, while also eliminating most other lawn pests, but there are certainly other effective products. Make sure that they contain either carbaryl or trichlorfon, and apply at rates that control white grubs.
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