Maggots squirming across a kitchen floor, or better yet the counter tops, are a certain reason for a homeowner to call a pest control firm. There is just something about these important recyclers that give us the creeps. In a home these will nearly always be blow fly larvae, and the two most likely sources are going to be dead animals, and recently dead, or filthy garbage that has not been disposed of for awhile. In a home it may be more likely that the dead animal is the culprit, as really dirty garbage receptacles may offer a noticeable and unwanted odor that alerts the homeowner to that problem. However, OUTdoors the rotting garbage can be much more possible when dumpsters or garbage cans are not emptied on that weekly basis and the contents begin to rot. This will lead to maggots crawling out and across patios or garage floors.
This is the nature of the blow fly larvae - they tend to leave what they have been feeding on to move some distance away until they find a small, protected crevice to get into so they can pupate. This migration is what brings them to our attention. When a dead rat or bird is in an attic the blow flies definitely are going to find it. This is their role in Nature, and they tend to make a single pass through that recently killed or dead animal. You will not have blow flies feeding on and emerging from some carcass that has been lying around for a couple of months, so in your case these 3 episodes with maggots represent at least 3 separate dead animals somewhere in the home. You often will be able to smell the distinctive odor or a rotting corpse, but when it is a smaller animal in a more ventilated area, such as the attic, the odor may not move down into the living areas. The maggots, however, will fall into light receptacles and other openings in the ceiling and from there down onto the counters and floors below.
Control, in a sense, is simple. You need to carefully inspect to find the source of the problem. If this were a customer's home the first question you might ask is "have you done any rodent control yourself lately?", and if the answer is that they tossed some bait blocks up in the attic then the source probably is going to be a dead rat. The difficulty is in finding it, but this needs to be done, and the carcass removed (while wearing gloves) and disposed of in a sealed plastic bag. Then, the area it rested on should be sanitized and deodorized and possibly even treated for the parasites (fleas, mites, etc.) that likely were on that animal and now are wandering around the area looking for a new blood host.
If the carcass turns out to be within a sealed wall then it may have to be a waiting game. Ideally the carcass is still removed so that it is over and done with, as leaving it there will ultimately lead to the flies, then the carpet beetles, and to the other scavengers in the lineup that decompose this leftover material. But, if it cannot be accessed directly you may want to dust within the void to kill the insects and then provide some deodorizing technique to minimize any smell that will linger until the carcass is completely dried. This may be with the use of deodorant bags such as the Earth Care products.
You inspection should include both inside and outside, and a careful look at the waste storage for the home. It still could be a large plastic bag of garbage that has been forgotten and left for too long. But, dead rats are a very common source in homes and a big reason that rodenticide labels must be followed with respect to their instruction to remove all dead or dying rodents as quickly as possible. This also emphasizes the reason that using rodent poisons indoors can lead to this secondary problem, and why trapping is a better idea.
Mr. Pest Control
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Please note, Mr. Pest Control is answering questions supplied by PMP customers across North America. His answers are generated from industry and manufacturer-provided information. The answer may not be specific to the laws and regulations for your State, Province, Territory or Country. In addition, products mentioned may not be registered and or available in all areas. Always check with your local Univar office for specific information to your area. Always read and follow label directions.