Harvest Mites

The Harvest Mite (Trombicula Autumnails) is, as you might think, a species of mite that frequently infect hosts during the fall, hence the name “Harvest”.


Like other parsites, Mites, such as Ticks and Fleas, require a blood meal to survive and to evolve through their life cycles. However, they do this a little differently to their peers.

Once a female Harvest Mite has laid an egg, the egg remains dormant for six days, after which, the non-feeding pre-larvae emerges.

Within a week, the pre-larvae grows into a larvae and congregates with others of its kind in large groups, usually in long grass, low bushes or plants.

While still in the larvae stage, the Harvest Mite is parasitic, it needs a warm-blooded host in order feed and develop into adulthood.

Any mammal will do but the most common victims are you, your dog or your cat. Once a hand, foot or paw comes in contact with a particular area of grass, bush or plant that is infested, the larvae will swarm.


The Larval Stage

Once they have attached to the host the larvae, commonly called ‘chiggers’, pierce the skin and inject a powerful digestive enzyme that degenerates the hosts skin cells. This is done through a tube formed by hardened skin cells called a stylostome. The larvae aim for thinly haired areas of the body as it is easier for them to pierce the skin here. 


The Chiggers will continue to feed like this for 2 – 3 days. In this time it will also grow 3 – 4 times its original size. Their appearance is reddish, orange in colour and can be seen on the skin of your dog or cat. After feeding on you, your cat or dog for a few days the harvest mite will drop off and complete their life cycle. In the adult stage the mites do not feed on blood but instead eat vegetation.


Harvest Mites On Cats 

There are many areas on a cat where a larvae may become attached. They are most likely to be found on areas with less hair such as in and around the ears, the chin and mouth, under the front legs, under the back legs, the lower abdomen and between the toes. This is not an exhaustive list and larvae can be found anywhere on cats.

Due to the physical symptoms your cat may exhibit if infested with harvest mites, many people think that the harvest mites burrow under the skin, however this is not the case. As the harvest mite feeds on your cat the enzymes which they inject irritate your pets’ skin. It is this intense itching that causes the cat to scratch or chew itself and inflict the injuries which are visible for you to see. In mild cases these can be small crusted spots but in severe cases can be raw, bleeding areas on your cats’ body and can also result in hair loss.

An additional problem that can arise from these skin lesions is the risk of secondary infection. Having open wounds on the skin of your cat can leave the door open for bacterial infections such as Pyoderma which may need to be treated with antibiotics.

Owners of cats that are frequently targeted by harvest mites should also be aware that in time their pet may develop an allergic reaction to the harvest mite’s digestive enzymes which may result in severe clinical symptoms.


What Causes Harvest Mites to Itch?

The itching in your dog or cat is caused by their reaction to the Harvest Mite’s digestive enzymes.

These enzymes may trigger rubbing, biting or scratching in your pet, which may also become infected with bacteria if left untreated.

Owners should also be aware that their pet may have an allergic reaction to the Chigger’s enzymes which may result in sever clinical symptoms.


How is a harvest mite infestation diagnosed?

Harvest mite infestations in cats, dogs and humans are usually found in late summer and autumn, as this is when harvest mite larvae need to feed on a blood meal to develop into adults. 

You may suspect that your cat or dog has an infestation if they develop a sudden onset of scratching or chewing. The scratching and chewing will be caused by the intense itching of harvest mite bites.

Sudden, intense itching is a common symptom among many hosts of ectoparasites, so the symptoms alone are not a conclusive diagnosis of harvest mites. However if your pet develops these symptoms during this specific time of year there is a good chance that harvest mites are the culprit.

If you suspect your dog or cat to be a host to Harvest Mites, have the issue correctly diagnosed by your veterinarian. Depending on how many mites are present, you vet may need to examine by taking a skin scraping and viewing it under a microscope.


Harvest Mites Treatment

Unfortunately, there are currently no products licensed specifically for the treatment of Harvest Mites in cats and dogs. Some flea treatments are effective in treating harvest mites when applied correctly. Using a treatment with a good residual strength will help keep harvest mites away from your cat and dog.

If you think your cat or dog is at risk of infestation by harvest mites then your vet will be able to advise you which treatments would be the most suitable.


Preventing Harvest Mites

Another way to prevent harvest mite larvae attaching to your pet is through modifying their routine.

Harvest mites are only active during the day, so you can reduce the risk by limiting exposure in areas where they may be. Harvest mite larvae can be found on lawns and in areas of longer grass and shrubbery. Limiting the amount of time your pets spend laying out in the garden may be a good way to stop the possibility of a harvest mite infestation.

For dogs, if you routinely go for walks in the afternoon, you could try heading out a little earlier or later in the day when temperatures are lower and the larvae are less active.