Mary Allen
Summer – sun – autumn grass mites! Nasty itching and lots of small red wheals after the foray through the meadows are mostly due to them. Read here how you can protect your animal and what helps against itching.
What are Fall Grass Mites?
Autumn grass mites (Neotrombicula autumnal) are widespread parasites in Germany, which are also known as autumn mites, harvest mites, hay mites, and grass mites.
Adult autumn grass mites feed on plant debris on the ground, so they are vegetarian. Only the orange-red larvae of the autumn grass mite are after animal food. They crawl up plants (up to about knee height) mainly between July and October and infest passing wild animals, dogs, cats, and humans. Autumn mites are found in large numbers, especially in low grass, i.e. on meadows and lawns, or in piles of leaves.
Autumn grass mite larvae don’t sting, and they don’t really bite either. They scratch the top layer of skin with their mouthparts, dissolve the tissue with a salivary enzyme and drink it. To do this, they first make a suction tube (stylostoma) out of their saliva, through which they can slurp their meal. The larvae only drink blood if they accidentally damage a small skin vessel.
If the mites are full after a few hours or (up to 3) days, they drop and develop into adult, vegetarian mites. They are often removed earlier by scratching or scouring.
Although autumn grass mites don’t stay on the body that long: the itching caused by their saliva can last up to two weeks. Most people – and probably animals too – find mite bites much more distressing than mosquito bites.
Autumn Grass Mites: How Do I Recognize an Infestation in Dogs and Cats?
It is typical that the autumn mite larvae usually appear in packs and have a preference for warm, thin areas of skin that are not very hairy. Us humans, for example, like to crawl into the back of our knees or further to the edge of our underwear. In dogs and cats, autumn mites are mainly found in areas of the body that have been in contact with the ground:
- Paws, legs (e.g. between the toes)
- Abdomen, chest (e.g. in armpits, groin)
- Head (e.g. on the chin, in the crease of the ears, around the eyes)
The autumn grass mites leave behind many small red wheals, also known to humans as harvest dross. Dogs and cats are sometimes so badly infested that they appear to be suffering from mange.
If they are still on the body, the tiny larvae, around 0.3 mm in size, can be seen as orange-red dots.
Fortunately, autumn grass mites do not transmit diseases in Northern Europe. They are also not transmitted from animals to humans or vice versa. So their bites are annoying, but usually not dangerous. However, sometimes dogs and cats experience allergic reactions that require veterinary attention.
How Can I Protect Dogs and Cats from Autumn Grass Mites?
Avoid contact with autumn grass mites
It is best to avoid any contact with the annoying mite larvae. Avoiding an infested meadow while walking the dog is often relatively easy. If the autumn grass mites are out and about in your own garden, it becomes more difficult to avoid them. Frequent lawn mowing and watering can help get rid of the mites. However, it is important not to dispose of the lawn clippings on the compost (where rodents or birds could become infected).
Remove mite larvae after being outdoors
It is best to remove the autumn grass mite larvae before they have found a cozy place to eat. That’s why it makes sense to have a fur check when you get home. They are relatively easy to get rid of immediately after a walk by washing off vulnerable parts of the body (especially paws) or wiping them with a damp cloth. Even when combing, some mites (since they are so small but probably not all) are removed from the fur.
If you only discover the mites after they have already started their meal, you can kill them with special shampoos or sprays from the veterinary practice. Oil is also said to help if applied directly to the larvae by suffocating them.
Autumn grass mite repellent spots or sprays
Autumn grass mites can be repelled with products containing natural pyrethrum from chrysanthemums or its laboratory-made derivatives, the pyrethroids (e.g. permethrin). These active ingredients not only drive the pests away but kill them on contact by paralyzing their nervous system.
The proverbial ancient Romans used pyrethrum powder from dried “insect flowers” to protect themselves from vermin such as ticks, lice, fleas, and mosquitoes. Since natural pyrethrum is quickly degraded by UV light, the sprays available today have to be applied daily.
Synthetic pyrethroids have a significantly longer and stronger effect than natural pyrethrum. You can buy them as part of tick remedies as spot-on (for dogs) or sprays for dogs and cats in every veterinary practice or pharmacy. According to the ESCAPE parasitologists, there are currently no repellents explicitly approved for autumn grass mites.