Green June bugs, cicada killer wasps and lawn rust

By John Fulton

[July 07, 2010]  A large, green beetle that sounds like a bumblebee when it flies has emerged in the last week. No, it isn't a Japanese beetle on steroids. It is a green June bug. These insects also have a grub stage but are not usually pests. They tend to lay eggs in places high in organic matter, such as flower beds, under shrubs, in compost piles, gardens and manure piles. The adult beetle can cause damage to soft fruits such as grapes, peaches, apricots and plums. It is actually called a fig eater overseas. Products such as bifenthrin, permethrin and Sevin are effective in controlling the adults. Remember, under hot conditions, products such as permethrin and bifenthrin may last for only a few days.

Cicada killer wasps

The cicada killer wasps will return shortly. They are actually considered beneficial insects because they control cicadas and katydids. This wasp gets its common name due to the fact that it hunts and supplies its nest chambers with a cicada, which becomes a food source for the young wasp. Cicada killers are a nuisance pest, especially when nesting in large numbers in a play area or near the house. People get concerned because the cicada killers resemble giant yellow jackets.

Cicada killers are about 2 inches long and black to red, with yellow-banded markings on the abdomen. The head and transparent wings are reddish-brown. They are not dangerous, but they are intimidating.

Cicada killers are solitary wasps, with the female digging a 6- to 10-inch burrow (one-half inch in diameter) in the ground. A pile of soil typically surrounds the entrance. The female locates and stings a large insect such as a cicada or katydid and then brings it back to the burrow. She places the insect into a chamber and lays an egg on it; sometimes she puts two in a burrow but lays an egg on only one. She then covers the burrow, digs another and repeats the process. The egg hatches into a grublike, legless larva that consumes the paralyzed insect. Full-grown larvae overwinter in the burrow, pupate in the spring and emerge as adults during the summer, usually in July and August.

Cicada killers are unlikely to sting a person. Wasp and bee stingers are modified egg-laying devices (ovipositors), so males are not able to sting. Females may sting if crushed, either by being stepped on with bare feet or grabbed with bare hands. Treatment of burrowing areas with a pyrethroid insecticide or carbaryl (Sevin) may reduce problems.

Lawn rust

As grass growth slows, rust will be one of the lawn fungi we are dealing with. Rust appears as an orange or yellowish-orange powder (spores) on grass leaf blades, especially in late summer to early fall when the weather is dry. Rust typically develops on lawns growing very slowly. Overall, the turf may assume a yellow, red or brown appearance. Rust spores can easily be tracked into homes. Other turf diseases, such as dollar spot and brown patch, are also prevalent.

Low fertility (in particular nitrogen) and high temperatures slow down turf growth, allowing rust to develop. Heavy dew and light, frequent rainfall add to the ideal conditions for rust to develop. Warm, cloudy, humid weather followed by hot, sunny weather also favors rust development on lawns. Kentucky bluegrass, perennial ryegrass and tall fescue are all affected, depending on cultivars. Rust spreads through air, water, shoes, equipment and sod. Rust may weaken turf grasses and make them more susceptible to other problems. Fungicides are rarely suggested on home lawns for rust control. Focus on the listed cultural practices described above.

[By JOHN FULTON, University of Illinois Extension, Logan County]