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The Landscape Alerts
Original Source:Nancy Hinkle, UGA Entomologist
June 27, 2011
The cicada killer wasp is the largest wasp in Georgia. The cicada killer wasp is almost two inches long. Although intimidating in appearance, these wasps are not something we humans have to worry about. Cicadas, on the other hand, should be very afraid. Cicada killer wasp adults feed on nectar but use paralyzed cicadas to feed their young.
Female cicada killers are hard to provoke to sting. The female uses her stinger to paralyze her prey (cicadas) rather than in self defense. The female’s attention is focused on providing food for her babies, so she poses little threat to humans.
Cicada killers prefer to nest in sandy open sunlit areas. As the female digs, she kicks out soil that forms a semicircle around the burrow opening. She burrows six to ten inches into the ground, prepares a chamber, catches a cicada to fill the chamber, lays an egg on the cicada, and seals the chamber. She may do this over a dozen times in one burrow.
When a female finds a cicada, she paralyzes it with her stinger, straddles it, and attempts to fly with it to her burrow. Because the cicada typically weighs more than she does, these flights are usually hops, with more dragging than gliding.
The egg hatches in a few days and the larva feeds on the paralyzed cicada until nothing is left but a shell. Then the wasp larva pupates within the burrow, remaining there until the next spring.
Males cannot sting; their only defense is intimidation. They patrol the nesting area, trying to divert attention away from the female, allowing her to provision her nest with cicadas. Meanwhile the male is using threatening tactics to distract potential predators. He may even dive bomb perceived threats. Since the males do not have stingers, they are completely harmless. They must rely on bluff, bluster, and bravado to protect their families.
Because cicada egg laying can be damaging to trees and shrubs, cicada killer wasps are very beneficial, providing free biological control. However, homeowners who do not want these wasps around can modify their lawn to be unappealing. A thick healthy turf with no bare spots will exclude cicada killer wasps. If turf is thin in nesting areas, identify turf problems that make the turf weak and correct them.
Cicada killer wasps will be active foronly a few weeks and will be gone by mid-August in most of Georgia. If someone is bothered by these wasps, late July and early August would be a good time to take their vacation.
For more on cicada killer wasps,
Photo credit - Nancy Hinkle, University of Georgia, Bugwood.org
Original Source:Will Hudson, UGA Extension Entomologist
July 11, 2011
June and July are excellent times to prevent white grubs in turf. White grubs live in the soil and feed on the roots of turf. Most white grubs have a one year life cycle in Georgia. Adult beetles lay eggs in late spring or early summer. The eggs hatch into grubs which feed and grow through the summer and fall, then dig down to spend the winter deep in the soil. They become active as the soil warms in the spring, and feed for a few days to a few weeks, depending on the species. They then turn into pupae before emerging as adult beetles to continue the cycle.
White grubs are the immature stage of Scarab beetles like green June beetles, Japanese beetles, chafers and others. The scarabs are a large family of beetles, and there are perhaps two dozen different species of white grub that might be found feeding on the roots of turf in Georgia. Included in this group are some of the most serious insect pests a turf manager will face.
White grubs damage turf by feeding on the roots during the summer and fall and, to a lesser extent, in the spring before pupation. Symptoms of white grub damage are similar to other factors that damage the root system - disease, soil compaction, poor fertility, or drought.
Except for the green June beetle, grubs never come to the surface until they become adults. The only way to tell if a lawn is infested is to dig the grubs up.
To scout for white grubs, cut 3 sides of a square of turf and lay the grass back like a carpet. Dig gently in the soil to a depth of 4 inches and count the grubs you see. It is important to identify the grubs before you treat. The potential for turf damage is dependent on the number and types of white grubs present. Your county agent can help identify grubs or see the publication White Grub Pests of Turf on the UGA Extension website.
It is easiest to find white grubs in early spring and late summer (late August) when they are larger and easy to see. That is not the best time to treat, however. Treatments are more effective if applied while grubs are small. In most of Georgia, this means application in June or July for best control. Once white grubs get bigger, there are fewer effective options and higher pesticide rates will be required. Good soil moisture and watering in the pesticide is also important. See White Grubs of Turf for good information on control measures.
Contact your local Extension Office for more information or consult the Georgia Pest Management Handbook for current pesticide recommendations.
Photo of white grub by Alton N. Sparks, Jr., University of Georgia, Bugwood.org