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Watergrass and Cicada Killer Wasps 
By John Fulton

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[August 05, 2016]  Watergrass - Watergrass is one of those names that means different things to different people. In our area, the main two weeds called watergrass are crabgrass and yellow nutsedge. Nutsedge isn’t even a grass, hence the name. It is easily identified by its triangular shaped stem.

Control in lawns is usually accomplished with bentazon (Basagran) or halosulfuron, and neither is something you usually find in the local garden shops. Roundup can help suppress it, but isn’t very effective on the mature plants – and it will also kill your grass. Usually you need at least two applications 10 days or so apart at the minimum.

The other main weedy grass called watergrass is crabgrass, and at this point it will probably just need to run its course for the season. This grass is an annual which germinates from seed each year. Sometime next month, it will brown out and be done. Of course, that doesn’t help with the lawn this growing season, especially since it stays wet most of the day.Next year, a preventative treatment could be applied early and repeated 6-8 weeks later.

Cicada Killer Wasps



The cicada killer wasps have returned! They are actually considered beneficial insects because they control cicadas. 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 cicada killer. Other food sources could include katydids and grasshoppers. We are getting cicada killers now because of the beginning emergence of the dogday cicada. 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 yellowjackets.

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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 (1/2 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 an adult during the summer, usually in July and August.

Male cicada killers establish aerial territories and patrol for intruders. A male cicada killer drives off other males that enter his territory and attempts to mate with females. Anyone else walking into the territory is typically confronted by a very large wasp, which hovers in front of the face and zips to the side and back. However, after determining that the "intruder" is not a rival, the wasp ignores the individual.

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.

Cicada killers are more common in areas with bare soil, so mulching, planting ground covers, or putting down sod can reduce problems. Applying permethrin, bifenthrin, another synthetic pyrethroid, or Sevin (some suggest the Sevin dust gives better control) to the burrowed area should kill females in high traffic areas. Once females are gone, males leave. In home yards, sandboxes can be covered with a tarp when not in use, as this deters the wasps (and also keep cats out). Sand below swings, jungle gyms, or other playground equipment is a popular site for the cicada killer. Raking the sand may discourage the wasps, or you could use mulch instead of the sand.

[By JOHN FULTON, COUNTY EXTENSION DIRECTOR SERVING LOGAN, MENARD, AND SANGAMON COUNTIES]

 

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