Flies & Dead Rats

The Fascinating World of Blow Flies: A Comprehensive Guide To The Flies Found On and Around Dead Rats!

Discover how dead rat flies or blow flies help get rid of the smell and dead bodies of rats and other dead animals in and around your home. Blow flies might be your best friends?

What Are Blow Flies and How Do They Help Us Get Rid Of Dead Rats?


The flies that interest us, are called the "true flies" from the order Diptera and are small insects that are responsible for removing and recycling huge quantities of waste both animal and plant in origin. These flies are able to very easily rid us of carrion, making them beneficial to the ecosystem, and in some ways humans too.


There are estimated to be over 100,000 different species, yet only a small proportion are considered important pests, both as a nuisance and as vectors of disease (distribution of bacteria, viruses, and other microorganisms).


Blow Flies:


Blow flies are also commonly referred to as "carrion flies". These insects are named for their association with dead animals and their role in the decomposition process.


The name "blow fly" comes from the Old English word "blæwfluga" which means "fly of the meat". Other common names for blow flies include bluebottle flies and greenbottle flies. These names are often used to describe specific species within the family Calliphoridae, such as the bluebottle fly (Calliphora vomitoria) and the greenbottle fly (Lucilia sericata).


In this article, we aim to provide a comprehensive guide to blow flies, exploring their anatomy, behaviour, habitat, and importance in our ecosystem. Flies are much maligned, but as you will learn are essential.


Anatomy and Physical Characteristics of Blow Flies


Blow flies have a distinctive appearance, with a metallic or iridescent body colour that ranges from green to blue to copper.


They have two large compound eyes that are positioned on either side of the head, and short antennae. The wings are clear and have a characteristic “V” shape when viewed from above. The females have a sharp ovipositor that is used for laying eggs.


The body of a blow fly is segmented, with three thoracic segments and seven abdominal segments. The mouthparts of the blow fly are designed for liquid feeding, and the larvae feed on decaying organic matter that include dead rats.


Adults will feed on organic waste but also serve as pollinators to many plants with high protein pollens and yellow flowers. A classic example of this in the UK is the common ivy blossom that attracts many different species of insects in September and October.


Behaviour and Life Cycle


Blow flies are strong fliers and are attracted to odours associated with death and decay. The female lays her eggs on or near a decomposing animal, and the eggs hatch within 8-20 hours into larvae, also known as maggots.


Maggots are legless and worm-like, with a moist, translucent appearance. They feed on the decaying organic matter and grow rapidly, moulting their skin several times. After several days, the larvae pupate and eventually emerge as adult blow flies.


The entire life cycle of a blow fly feeding on dead rats can take as little as seven days, and in some species, multiple generations can occur in a single year.


Habitat and Distribution


Blow flies can be found globally and their distribution is limited only by temperature and humidity. They are commonly found in temperate and tropical regions and thrive in environments with a consistent supply of carrion or other decaying organic matter.


In such environments, they can be found in a variety of habitats including forests, fields, and urban areas. The presence of blow flies can indicate the presence of decaying organic matter and their distribution can provide important information about the ecosystem and its functioning.


Importance in the Ecosystem


Blow flies play a crucial role in the ecosystem as detritivores. They help to break down dead organic matter, returning important nutrients back to the soil. They also serve as an important food source for other animals, including birds, reptiles, and amphibians.


In addition to their ecological role, blow flies are also of significant importance in forensic entomology.


The life cycle and presence of blow fly larvae on a decaying body can provide important information to investigators, such as the time of death and the presence of any drugs or toxins.


what is the life cycle of the blow fly?


The life cycle of the blow fly typically consists of four stages: egg, larva, pupa, and adult.


  1. Egg Stage: Female blowflies lay their eggs near sources of food, such as carrion or other decaying organic matter. The eggs are usually laid in clusters and are white or yellow in colour. They hatch into larvae within 24 to 48 hours.
  2. Larval Stage: The larvae, commonly referred to as maggots, feed on the decaying organic matter. They grow rapidly and moult several times during this stage. The larvae are usually creamy white in colour and have a cylindrical shape. This stage typically lasts for several days.
  3. Pupal Stage: The larvae pupate within a protective cocoon and undergo metamorphosis into the adult form. This stage lasts for several days to several weeks, depending on environmental conditions.
  4. Adult Stage: The adult blow fly emerges from the pupal case and begins to mate and lay eggs. The adult has a lifespan of several weeks to a few months, during which it will mate and lay several times.


This life cycle repeats itself continuously, providing a constant source of blowflies in their habitat. Understanding the life cycle of the blow fly is important in fields such as forensic entomology, where their presence on a dead body can provide information about the time of death.


Understanding their role in forensics makes these common pests a little less of a nuisance and almost the hero of this story.


How Long Before Flies Reach A Dead Rat?


Once a pest control poison is applied to a rat infestation and the rat poison has takes effect, the rat quickly dies. However, it takes many hours, days, or even weeks, before the insects access the carcass or carcasses.


Temperature plays a vital part in this process because cold conditions render the insects dormant. Once the temperature rises above 10°C, we see them emerging from their long winter sleep, looking for a meal and a chance to reproduce.


Cold weather makes it unlikely flying insects will be around to notice dead rodents. Turning on heating systems will sometimes create a temperature rise in the properties cavities, stimulating overwintering insects to emerge and be attracted to the dead rodent.


Flies are our friends - the sooner they get into a carcass, the sooner the smell goes!


When Do Flies From A Dead Rat Appear?


In most cases, flies from dead rats, rodents and birds emerge within a few weeks of maggot infestation.


The maggots or fly larvae, mature faster in warm conditions and develop sluggishly in colder weather. For this reason, it can be impossible to predict this time during inclement conditions.


Activity depends on where in the house the dead rats is. the most common type of areas are in the loft, crawl spaces, basement and wall and ceiling cavities.



How Long Will Flies From Dead Rats Last?


Once the blowflies larvae (maggots) begin to emerge from the dead rats in a house, they pupate and from pupae and metamorphosis, activity often starts with just a few large flies.


As the day progresses, the number of insects gets worse and worse, producing a significant potential physical food and health hazard. Dangerous disease causing bacteria should always be mitigated with good hygiene practices.


By the end of the first week, 500-1500 flies will have almost completely vanished and you should be satisfied that you are nearly rid of these miracle workers that are very well adapted to eat your dead rat.


Flying insect infestation is common with poison baits, so trapping should always be considered a first step in avoiding fly infestations. The downside is that a trap may take longer than poison because the rodents are neophobic, so they don't like new things in their environment.


Traps left untethered often get dragged back into wall cavities where the rats are not accessible so you still end up with a rat that takes ages to die, stuck in your walls, and the resulting odor. This makes the whole rat-trapping process a little pointless when compared to the speed and convenience of rat poison.


Most flies from rats in a house or building are dead within 30 days, although this can vary.


How Long Does A Dead Rat take To Decompose?

Dead rats can take many months to decompose. First, the fly larvae will enter the animal around the mouth and rear.


Once the fly larvae complete their job, moth and beetle larvae come in to eat the skin and fur.


This process can take two years!


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