flying insect beside house

Asked July 16, 2019, 11:34 AM EDT

For the past month I've noticed an increasing number of large flying insects alongside my house. I attach a photo showing a few in flight. Another photo is magnified to the point of being blurry but shows more of them together. I would guess they are approximately 2 centimeters long, have a black tail and a brown head with big eyes. They appear along the southeast facing side of my house in the morning (when it is very sunny there) and are gone by late afternoon when that part of the house is in the shade. I have not been able to detect a nest. They largely buzz along the ground in agitated circles and other seemingly random patterns. I would estimate in the mid-morning that the side of the house has approximately 500 of these flying insects. My guess is that they are carpenter bees that live in the ground but maybe they are burrowing into the wood along the side of my house. The 120-year old house has a stone foundation but is otherwise wood. I worry about this phenomenon because I fear they could sting members of my family, they could be damaging my house, and they make me afraid to be on that part of my property when they are there. What should I do?
Addendum: I also took a video showing them in flight but your site does not invite videos; if you want me to send that, then please tell me. More generally any other information that I can provide I gladly provide. I have walked the land carefully, repeatedly and imagine that I see small holes in the ground but have destroyed those holes with no impact on the insects.


Baltimore County Maryland

6 Responses

You do not have anything to worry about.
We can't tell you exactly what they are without a clear photo, but they are definitely not anything that would bore into or damage your house or sting you.
Just for comparison, here is our page on Carpenter bees, which are comparatively huge at 1/2- 1". They are seldom seen in groups.

These are acting like beneficial predators of pest insects, as there are insects, for instance scoliid wasps and mining bees that fly low over grass (sometimes in large numbers) as they hunt for pests to eat like grubs. They do not sting or bother people.
There are other beneficial and non-aggressive bees and wasps as well that only nest singly in the ground (tho there may be many near each other). They use their stinger for the insects that they catch and store for their offspring. They will not bother you, even if you walk through them. (We would not fill any holes. The majority of insects are good guys that we need for the web of life.)

Christine

Thank you for the information. I killed one and took a close-up picture beside a ruler and attach that as scoliid.jpg. Your response suggested this might be scoliid wasp. My reading online now suggests you are right. I have looked at
https://extension.umd.edu/hgic/topics/scoliid-wasp, https://en.wikipedia.org/wiki/Scoliidae, and a few other places. Based on the picture and my descriptions do you think this is scoliid? what species of scoliidae do you think I have? Despite your re-assuring words, I have a problem. My house sits on 3 acres and should these wasps be elsewhere on my land, I might not care, but they are increasing in numbers and spreading from the side of the house to the entrance to the house. My wife and child are afraid to use the entrance. Why do hundreds of these wasps daily for weeks fly exclusively beside one small patch of land approximately 50 feet by 20 feet alongside my house? From reading on the web, I gather they might be eating beetles and laying their own eggs in the ground where beetles might have been. I would have thought that they would exhaust the beetle supply. Is their big attraction now their own nests? What explains my particular phenomenon and what is likely to be the natural history for the next few weeks? How could I encourage them to leave my house entrance and go 100 feet from my house into the yard?

I made the preceding reply a minute ago but your system stamped me as anonymous but I would like to identify myself so that you continue to communicate with me.

What you have there is not a scoliid (which have metallic blue wings) but a solitary wasp called a Cicada Killer. They are very large and fearsome looking and understandably concerning to you and your family from looks alone.
It would be a great teachable moment though to share with them that they are beneficial, non-aggressive insects (the males may act territorial but they don't even have a stinger). The females singly dig a hole and lay an egg, then use their stinger to paralyze a cicada (the noisy buzzing insect in the trees right now) and bring it to the hole to serve as a food source for the baby.

Cicada killer wasps are considered beneficial because they reduce the cicada population and should be tolerated if possible. They usually will not bother people even when provoked. They are a solitary wasp but may appear in large numbers in good nesting sites such as sunny, well drained soils with large trees nearby to hunt cicadas. They are not around for very long.

There are no easy control solutions. Modify the habitat and make the area unattractive to burrowing. You might try to thicken your stand of turf by overseeding in the fall. Sometimes running a sprinkler in the nesting area over a period of time to saturate the ground during the day while the wasps are active. They do not like water and may lessen activity temporarily.

It must be stressed that mining bees are extremely beneficial insects, of considerable importance in the pollination of many different types of plants. Their burrowing does not harm vegetation and may actually be of service in overturning the soil. Furthermore, the activity of species is extremely brief, with the adult bees flying for only 2 to 4 weeks. In some instances, the bees observed are males flying about their territories; males cannot sting nor do they make burrows.


Christine

Christine, Your sharing your knowledge is helping me deal with my fear. Thank you for correcting me on jumping to the conclusion of scoliid and indicating that I have cicadia killers. I have now read https://en.wikipedia.org/wiki/Sphecius_speciosus which echoes what you said. Although you encourage me to leave these wasps alone, I might take advantage of your observation that watering the area during the day might encourage them to relocate.
Yours,

We are happy to help. Any time.
Everything we share is backed by Extension University non-biased, research-based science.
(Sometimes Wikipedia isn't, and it is not local to our area/environment either, so be careful).

Christine