What Are Mites? The Red Velvet Mite (Trombidiidae)

What Is the Red Velvet Mite?

The red velvet mite is an arachnid that belongs to the family Trombidiidae. There are thousands of different species of these velvet mites. The giant red velvet mite belongs to the species Trombidium grandissimum. We will briefly look at what mites are and then move on to the interesting red velvet mite.

The Trombidium holosericeum is another well-known species from the Palearctic ecozone which is the largest of the Eco-zones dividing the earth’s surface. Trombidium grandissimum is found in dry lands and deserts and has been seen widely in the northern parts of India.

Note: Palearctic Eco-zone is the largest Eco-zone and comprises of the terrestrial Eco-regions of Europe, Asia north of the Himalaya foothills, Northern Africa and the Northern and Central parts of the Arabian Peninsula.

The velvet mites found in sandy desert areas belong to the genus Dinothrombium and the ones found in organic soils belong to the genus Thrombium.

It is interesting how I decided to write an article on the red velvet mite. I have neither seen one nor heard about this mite until I saw a post of this mite from one of my followers on Instagram. I looked at the picture on my mobile (not a big picture, not macro shot) and asked if it was a crab, because the way its legs were arranged, resembled a crab. I got a response to say that it was a bug or some form of spider that was found in their village in North India.

At this point, I got too curious and looked for it on the internet. I looked for “red velvet spider” and instantly got the results. It was a red velvet mite. I gave a quick read and found it interesting and thought that I will share it in this community. This red velvet mite might be new information to you, or you might have come across these or known about these before.

What Are Mites?

Mites are small arthropods that belong to the subclass Acari and class Arachnida. The study of mites is called acarology. They are invertebrates (animals lacking a backbone) and range from microscopic size to about 0.5 cm. There are more than 45,000 to 48,000 species of mites that are known. Some are parasites and some are predators. Some feed on plants, fungi and organic debris.

Mites that live in soil can be found up to a depth of 33 feet. Mites found in water can survive in freezing cold to as hot at 50 degree Celsius. They are also found in desert sands and deep sea trenches.

Red Velvet Mites, from Munsiyari, the Central Himalayas, India

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Scientific Classification (Taxonomy) for the Velvet Mite

Kingdom: Animalia

Phylum: Arthropoda

Subphylum: Chelicerata

Class: Arachnida

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Subclass: Acari

Order: Trombidiformes

Superfamily: Trombidioidea

Family: Trombidiidae

Genus: Trombidium

Terms Explained:

Calyptostatic - A morphologically regressive state of the pre-larva; a featureless sac without legs or mouthparts

Ectoparasites - Any external parasitic organism

Hosts - An animal or plant that nourishes and supports a parasite

Spermatophore - A capsule or pocket inclosing a number of spermatozoa

Haemolymph - Circulatory fluid of insects. Haemolymph contains water, amino acids, sugars, salts, and white cells like those of white blood

Chelicerae - first pair of fang-like appendages near the mouth of an arachnid; often modified for grasping and piercing

Habitat of the Velvet Mite

• In India, these mites are found in dry areas. These mites are also found in woodlands and forest soil, litter, humus, moss and other terrestrial habitats like sandy desert areas and organic soils.
• They stay under the soil most of the year and come out of the soil only after a rain. They spend only a few hours outside the soil every year and during this time they look for food and mate.
• They are also found extensively in the palearctic zone and in a variety of other habitats that include deserts, moist soils, etc
• They look like miniature velvet cushions crawling everywhere.

Food of the Red Velvet Mite

• The velvet mites are predators and they feed on other invertebrates like small arthropods and their eggs, for example termites.
• The adult velvet mites look for food and feed on them for only a few hours every year.
• Depending on the species, the amount of food they eat per day varies. For example like 20 beetle eggs, 36 immature spider mites. Some species of nymph consume 49 to 54 prey per day and some adults consume 85 prey per day.

Characteristics and Behaviour of Red Velvet Mites:

• These mites grow around 1.5 cm up to 2 cm long, which is huge compared to other mites. For example the giant Indian red velvet mite (Trombidium grandissimum). There are so many different velvet mites found all over the world and they all come under the family Thrombidiidae and they grow to different sizes.
• The adult mites are bright red colour and their body has a velvety coating that has fine red colour hairs which sometimes act as feelers.
• They have two tiny eyes, but they sense their prey through vibrations and chemicals. They use their front pair of legs to sense where they are going.

• The adults have 4 pairs of legs while the larvae have only 3 pairs of legs. The four pairs of legs in an adult are arranged in a rare pattern. Two legs each in four spots of the underside of the body (See picture to the right hand side)
• They do not have distinctive body segments like the other arthropods, but a single body segment.
• The red velvet mites have chelicerae that they use to suck food out of their host and for feeding.
• These mites are active during the day especially when there is sunshine and hide beneath the soil during the night. They hibernate during winter.
• They are not eaten by any predators, simply because they taste very bad, but they do have a few enemies. The adult mites sometimes eat each other and sometimes are even parasitized by larvae.
• They secrete anti-fungal oil and their haemolymph also contains antifungal properties.
• They are harmless to humans

Reproduction in Red Velvet Mite:

The mating in velvet mites is an interesting one in the form of a mating dance. While mating, the male deposits spermatophore on twigs or grass blades and invites the female by making an intricately woven silk path. If another competitor male finds this, he will break open the spermatophore and drop his own.

The female if impressed with the male, will sit on the spermatophore and it gets fertilised.

The development and lifecycle of the velvet mite consists of the following steps. In the steps below

• The pre-larvae stay close to the area where they hatched from
• The larvae are ectoparasites
• Protonymphs and tritonymphs are calyptostatic,
• The deutonymphs and adults are free living predators.

Larva of Red Velvet Mite on Hosts

Larval velvet mite on host

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Egg - The eggs are laid by the female in the soil or humus or litter or sand. The number of eggs laid depends on species. The female lays as many as 60 eggs to 100,000 eggs according to the species and they are laid between the months of March and July. Some species lay eggs during the Autumn season.

Pre-larva - The eggs hatch after a month or two depending on the conditions of the environment. The larvae emerge out of the eggs and stay there for one day to few days from where they hatched depending on the species. This is pre-larva stage

Larva - They then disperse. The larvae are ecto parasites and live as parasites on insects like grasshoppers, crickets, locusts, aphids, beetles and on arachnids. The larva has only six legs. This parasitic stage continues for a week or sometimes two weeks.

Note: The larva inserts its chelicerae into the exoskeleton of the host and starts sucking on the haemolymph inside the insect through the wound. The host can walk and fly. The larvae move or fly along with the host and drop off in new places and move into the soil. The parasitism does not kill all the hosts; however this has an effect on their survival, health and reproductive rates. The health of the host also depends on the number of parasites on each host.

Protonymph - In this stage the protonymphs are calyptostatic and develop inside the cuticle of the larvae. They lie inactive like a pupa.

Deutonymph - During this stage the deutonymphs emerge out of the cuticle, either in summer or Autumn season. They have eight legs and they are active predators. The look for food on the surface of the soil and in plants. Some species can consume several aphids a day.