This is a blog post by Doctor of Plant Medicine student, Matt Borden.
The three introduced species of mole crickets. Left: shortwinged mole cricket. Center: tawny mole cricket. Right: southern mole cricket. Credit: W. C. Adlerz, University of Florida.
It’s that time of year! Mole crickets are adults again. During the summer months, juvenile mole crickets are busy feeding and growing larger. During the autumn, many of these insects will develop into hungry adults, which can cause substantial injury to turf.
At night, adult mole crickets fly from site to site in search of mates, while adults and nymphs also burrow through the soil, feeding on roots and tubers. This disturbance and activity is typically most apparent and severe after warm and rainy weather. Narrow, raised tunnels just below the surface are a sure sign that southern or tawny mole crickets are present. These exotic insects will feed on any turfgrass, but bahiagrass and bermudagrass are most susceptible, followed by St. Augustinegrass. During the late fall and throughout spring, moist soils and lights attract adults. You can make your lawn less appealing by keeping the yard dark and not irrigating in the evening.
Natural enemies of mole crickets
Larra bicolor is an important natural enemy of introduced mole crickets. By planting more wildflowers, such as this shrubby false buttonwood, you can help support these wasps and attract more of these valuable insects to your property. Credit: Lyle Buss, University of Florida
After midsummer, using insecticide is generally not an effective or economic management approach. Luckily, there are a couple of natural enemies that can help reduce mole cricket numbers. The larra wasp, Larra bicolor, is an attractive insect with dark wings and a red abdomen. Attracting more of them to your property will aid in long-term mole cricket control because the eggs they lay on mole crickets hatch into larvae that consume the mole cricket. Plant shrubby false buttonweed (Spermacoce verticillata) to provide Larra wasps with an excellent nectar source throughout the autumn. A beautiful native wildflower species that is also attractive to this beneficial insect is blue mistflower (Conoclinium coelestinum).These wasps are solitary (without a large nest to protect) and do not sting humans. If you would like to learn more about Larra wasps, visit the Featured Creatures page.
Larra wasps aren’t the only natural enemy that was introduced to Florida to control these invasive pests. The insect-parasitic nematode, Steinernema scapterisci
, was commercially produced and applied to pastures, golf courses, and sod farms for several years. However, this ceased around 2012 and the current status of these biological control organisms and their impact on exotic mole crickets is unknown. Our post-doctoral researcher, Pablo Allen
, is currently conducting research to determine if these nematodes are widely established in Florida and what effect they have had on invasive mole cricket populations.
Time-lapse video of insect-parasitic nematodes emerging from a southern mole cricket. Credit: Adam Dale