I have several burrows be... - Ask Extension
I have several burrows between the boulders in a retaining wall supporting a garden pond, which I believe are from Cicada Killers. Is it possible the...
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I have several burrows be... #149974
Asked August 29, 2013, 12:11 PM EDT
I have several burrows between the boulders in a retaining wall supporting a garden pond, which I believe are from Cicada Killers. Is it possible they would dig to a point of undermining the pond floor? I can live with the dirt piles if that's the worst that will happen...
Hennepin County Minnesota
Expert Response
Thanks for the photo. And I have seen great numbers of these this year in rocks and in turf.
Female cicada killers dig extensive tunnels where their young will be raised, displacing several pounds of soil in the process. Individual tunnels are can range from 30- to 70-inches long and may run 12- to 15-inches below the surface. Occasionally, it can result in some damage, such destabilizing a brick patio laid on sand. I suppose that pockets under the pond liner could be an issue and may be difficult to refill. This is an instance when control may be needed.
Large aggregations of cicada killers can build up over time. An estimated 40% of the developing larvae (a dozen or more per tunnel) may emerge as adults the following year so numbers can increase rapidly.
There are an average of 15 egg-shaped side chambers an a tunnel, each containing 1 to 3 paralyzed cicadas and an egg which hatches in 2 to 3 days. The grub-like wasp larva feeds for about 10 days, leaving only the cicada's outer shell. During the fall, the larva spins a silken case, shrinks, and prepares to overwinter. Development will be completed when wasps emerge next summer. There is one generation each year.
As you may know they are not usually harmful but females have significant stingers which they plunge into cicadas to inject venom that paralyzes them. Without doubt, their stings are painful. However, they are not aggressive and do not have nest-guarding instinct of honey bees and hornets. You can walk through areas where they are active without attracting attention.
Control may be desirable in an area where physical damage is occurring or insects is causing significant distress. Applications were made directly into the burrows or only to the entrances where the wasps contacted the insecticides as they entered and left. Effective active ingredients include permethrin and carbaryl. Broadcast sprays over the area where cicada killers were nesting were not effective in reducing their numbers. ALWAYS READ AND FOLLOW LABEL DIRECTIONS FOR SAFE USE OF ANY PESTICIDE!
Here is a link for more info.
http://blog.lib.umn.edu/efans/ygnews/2012/08/cicada-killers.html
Female cicada killers dig extensive tunnels where their young will be raised, displacing several pounds of soil in the process. Individual tunnels are can range from 30- to 70-inches long and may run 12- to 15-inches below the surface. Occasionally, it can result in some damage, such destabilizing a brick patio laid on sand. I suppose that pockets under the pond liner could be an issue and may be difficult to refill. This is an instance when control may be needed.
Large aggregations of cicada killers can build up over time. An estimated 40% of the developing larvae (a dozen or more per tunnel) may emerge as adults the following year so numbers can increase rapidly.
There are an average of 15 egg-shaped side chambers an a tunnel, each containing 1 to 3 paralyzed cicadas and an egg which hatches in 2 to 3 days. The grub-like wasp larva feeds for about 10 days, leaving only the cicada's outer shell. During the fall, the larva spins a silken case, shrinks, and prepares to overwinter. Development will be completed when wasps emerge next summer. There is one generation each year.
As you may know they are not usually harmful but females have significant stingers which they plunge into cicadas to inject venom that paralyzes them. Without doubt, their stings are painful. However, they are not aggressive and do not have nest-guarding instinct of honey bees and hornets. You can walk through areas where they are active without attracting attention.
Control may be desirable in an area where physical damage is occurring or insects is causing significant distress. Applications were made directly into the burrows or only to the entrances where the wasps contacted the insecticides as they entered and left. Effective active ingredients include permethrin and carbaryl. Broadcast sprays over the area where cicada killers were nesting were not effective in reducing their numbers. ALWAYS READ AND FOLLOW LABEL DIRECTIONS FOR SAFE USE OF ANY PESTICIDE!
Here is a link for more info.
http://blog.lib.umn.edu/efans/ygnews/2012/08/cicada-killers.html
