Since the European crane fly immigrated to Western Washington, turf grass and pastures have been providing free lunches every spring in larger and larger parts of the state.
The adults look a lot like very large mosquitoes, and their habit of congregating by the thousands on the sides of houses in late summer may cause some excitement (even though adult crane flies don't bite or sting).
Their Night Life Starts When Young
The worm (or larval) stage of this insect feeds from the first day it hatches. Their growth is rapid in the spring, and this is when most turf damage occurs. The young larvae seem to prefer green leaves and do most of their feeding at night. Feeding does continue during the day as they seek cover in and under the thatch and feed on the roots and thatch itself. Grass blades are often severed at the root crown.
Months Of Preparation For The Big Night
Crane flies winter as immature larvae in the soil. They may stay at this level of development for as long as 4 months. As the temperatures increase in spring, the larvae begin feeding again, and this is one of the periods when rapid growth occurs. On warm, moist nights and dark days, they'll feed on the surface, but generally stay within the top 1'' of the turf.
During April, the larvae go through their heaviest feeding period until they reach maturity. They then go into an extended period of inactivity. During late August and early September, the larvae quickly pupate, emerge as adults, mate and lay eggs for the next generation. A typical female crane fly adult emerges, mates, and lays all her eggs in a single night (whew!). She then lives for only 4 or 5 days. Eggs hatch in 11 to 15 days and larvae feed ravenously for the next two months during their second period of rapid growth.
How Many Is Too Many?
Determining if there lawn treatment services are necessary can be done a number of different ways. You can dig up several areas about 1 square foot wide and 1'' to 2'' deep, and count the number of pupae. Various studies indicate that on healthy turf any population over 20 to 25 per square foot indicates that a control application should be considered. The best control can be achieved during the larval (or worm) stage between January and March.
Remember:
- The crane fly larvae spend 11 months getting ready for one opportunity to mate each season.
- More than 20 to 25 pupating larvae per square foot in March usually indicate the need for treatment.
- Spring and fall are the two periods of rapid growth and heavy feeding.
If you're concerned about the crane fly, contact your neighborhood Spring-Green lawn and tree care professional for more information about our yard care and lawn treatment services. At Spring-Green, we're always happy to take a closer look for you.
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