Aug 21, 2011 – A Prowler In The Pool
QUESTION:
I pride myself in being good at pest ID's. Several days ago however, I was baffled by what appeared to be a hybrid bug/beetle creature crawling on the wall about 5 feet down UNDERWATER in my swimming pool. It has an oval-shaped back that looks like half an egg shell, maybe 1/2 inch long, and shiny, dark emerald green color with black spots. The closest thing in appearance would be a tick or cockroach, but my dogs do not have ticks, and I've never seen a tick with such a perfect shiny oval shape. After three days, it STILL is underwater, so unless it is sneaking out between 9-5 while I am at work, it seems to have no problem living underwater for long periods of time.
ANSWER:
Hi Tino. There is a nice variety of bugs that are happy to swim around in our pools for awhile, although generally after a few days of finding nothing to eat they will move on to more productive pastures. These insects normally live in nearby aquatic habitats, such as a local creek or lake or pond, but many of them can fly, and during the course of this excursion they may see a swimming pool and ..........well, water is water, and in they go. The group includes backswimmers and water boatmen (both true bugs that could bite if handled) and predaceous diving beetles and water scavenger beetles. I suspect you are looking at one of these, based on the shiny back and dark color. Take a look at this fabulous website - http://bugguide.net/node/view/195/bgimage and compare with some images there. This is Bug Guide and this page is the Dytiscidae, or predaceous diving beetles, and if you don't see the bug you have then put "Hydrophilidae" as a search word in the search field and compare with images of beetles in that family.
My initial thought was that you had one of the huge Predaceous Diving Beetles that are so common in California, and which frequently end up on the pavement at car dealerships, where they were attracted to the mercury vapor lights overhead. These fit your description except for the fact that the big ones I so often see are over an inch long and are a solid dark olive green color with no spots on them. However, you could just have a different species. All of these beetles are harmless to people and frankly should be enjoyed as a curiosity and cute visitor to the pool. Occasionally I am asked how to eliminate the various bugs that get into pools and there really is no chemical answer. You either have to wait for them to leave on their own or take the leaf-remover and yank it out and toss it in the garden, and then hope it does not crawl back in. For most of these bugs they can just be ignored and in a few days they leave. A clean pool is not going to have the food resources needed by these predatory bugs to keep them interested for long.
All the beetles and the bugs do have to breathe oxygen and must come to the surface for it on some regular basis. But, they manage to "hold" their breath for quite awhile, and it could be that the beetle simply sees you and is avoiding coming up while you are there. After all, you could be some bird trying to eat it, so when it sees movement above it stays underwater. So that's my bet on the ID - either Dytiscidae or Hydrophilidae, and the Bug Guide website will probably have images of exactly your creature.
View past Ask Mr. Pest Control questions.
I pride myself in being good at pest ID's. Several days ago however, I was baffled by what appeared to be a hybrid bug/beetle creature crawling on the wall about 5 feet down UNDERWATER in my swimming pool. It has an oval-shaped back that looks like half an egg shell, maybe 1/2 inch long, and shiny, dark emerald green color with black spots. The closest thing in appearance would be a tick or cockroach, but my dogs do not have ticks, and I've never seen a tick with such a perfect shiny oval shape. After three days, it STILL is underwater, so unless it is sneaking out between 9-5 while I am at work, it seems to have no problem living underwater for long periods of time.
ANSWER:
Hi Tino. There is a nice variety of bugs that are happy to swim around in our pools for awhile, although generally after a few days of finding nothing to eat they will move on to more productive pastures. These insects normally live in nearby aquatic habitats, such as a local creek or lake or pond, but many of them can fly, and during the course of this excursion they may see a swimming pool and ..........well, water is water, and in they go. The group includes backswimmers and water boatmen (both true bugs that could bite if handled) and predaceous diving beetles and water scavenger beetles. I suspect you are looking at one of these, based on the shiny back and dark color. Take a look at this fabulous website - http://bugguide.net/node/view/195/bgimage and compare with some images there. This is Bug Guide and this page is the Dytiscidae, or predaceous diving beetles, and if you don't see the bug you have then put "Hydrophilidae" as a search word in the search field and compare with images of beetles in that family.
My initial thought was that you had one of the huge Predaceous Diving Beetles that are so common in California, and which frequently end up on the pavement at car dealerships, where they were attracted to the mercury vapor lights overhead. These fit your description except for the fact that the big ones I so often see are over an inch long and are a solid dark olive green color with no spots on them. However, you could just have a different species. All of these beetles are harmless to people and frankly should be enjoyed as a curiosity and cute visitor to the pool. Occasionally I am asked how to eliminate the various bugs that get into pools and there really is no chemical answer. You either have to wait for them to leave on their own or take the leaf-remover and yank it out and toss it in the garden, and then hope it does not crawl back in. For most of these bugs they can just be ignored and in a few days they leave. A clean pool is not going to have the food resources needed by these predatory bugs to keep them interested for long.
All the beetles and the bugs do have to breathe oxygen and must come to the surface for it on some regular basis. But, they manage to "hold" their breath for quite awhile, and it could be that the beetle simply sees you and is avoiding coming up while you are there. After all, you could be some bird trying to eat it, so when it sees movement above it stays underwater. So that's my bet on the ID - either Dytiscidae or Hydrophilidae, and the Bug Guide website will probably have images of exactly your creature.
View past Ask Mr. Pest Control questions.
