Fun Fact: Ticks and Mites Are Related to Spiders and Scorpions

Are ticks and mites related to spiders?

These four animals share a common arachnid ancestor, meaning their biology is far more similar to each other than it is to ants, cockroaches or flies. For Sydney households, this matters because their shared traits mean pest control treatments for arachnids differ from standard insect treatments.

If you’re dealing with any of these arachnids around your Sydney home or business, for a full property inspection and tailored treatment plan, Contact Sydney’s Best Pest Control.

What core traits define an arachnid, compared to an insect?

All adult arachnids share four non-negotiable physical traits that separate them from insects. You can use these to identify any unknown pest in your Sydney home in under 10 seconds:

1. 8 legs as adults

This is the fastest check. Insects always have 6 legs as adults; every arachnid has 8. Juvenile arachnids may have fewer legs immediately after hatching, but develop the full 8 within their first few moults.

2. Two main body segments

Insects have three distinct body parts: head, thorax and abdomen. Arachnids have two: a fused head-chest called the cephalothorax (where legs and mouthparts attach), plus a separate abdomen. In mites and ticks, these two segments are fused so tightly they look like one single body.

3. No antennae or wings

All adult insects have antennae, and most have wings at some life stage. No arachnid ever grows antennae or wings — if your home invader has either, it is not an arachnid.

4. Chelicerae mouthparts

Instead of the chewing or sucking mouthparts insects use, arachnids have specialized pincer-like or piercing mouthparts called chelicerae. These appear as fangs in spiders, piercing tubes in ticks, and tiny pincers in mites and scorpions.

CSIRO’s 2024 Australian Urban Pest Survey estimates 80% of Sydney households will encounter at least one pest arachnid — most commonly redback spiders, bird mites or paralysis ticks — on their property each year.

How closely related are mites, ticks, spiders and scorpions to each other?

While all four are arachnids, some are far closer cousins than others. Their evolutionary relationships are split into distinct scientific subclasses and orders:

The Acari subclass: Mites + ticks

Mites and ticks are so closely related they belong to their own exclusive arachnid group called Acari. In fact, ticks are not a separate group at all — they are simply highly specialized, obligate parasitic mites that evolved to feed exclusively on the blood of mammals, birds and reptiles.

Most mites are tiny (less than 1mm long) and feed on dead skin, plant matter or other small organisms. Ticks grew larger, developed stronger piercing mouthparts and a tough, expandable outer shell to hold large blood meals.

Other distinct arachnid orders

Spiders form the order Araneae: specialized arachnids that produce silk from abdominal glands and inject venom via hollow fangs to subdue prey. Scorpions form the order Scorpiones: defined by their large front pincers and segmented tail tipped with a venom-injecting stinger. Neither group is more closely related to mites/ticks than they are to each other.

For Sydney residents, the closest relative rule has real health implications. NSW Health 2025 data records around 1,500 paralysis tick (Ixodes holocyclus) presentations to Sydney metropolitan hospitals annually, with peak risk spanning September to February across bushland-edge suburbs from the Northern Beaches to the Blue Mountains.

For urgent Sydney tick, mite, spider or scorpion treatment and same-day express callouts, call our team now on 1800 819 189.

How do I tell common arachnid groups and insects apart at a glance?

Use this side-by-side comparison to quickly identify any small home invader in Sydney:

Why are mites considered the most diverse arachnid group?

Mites are the unsung champions of animal diversity, and far outnumber every other arachnid group combined by almost every measure.

Per the Australian Museum’s 2026 Arachnida Collection records, there are over 50,000 scientifically named mite species, with researchers estimating the true total could top 1 million species globally. By comparison, there are roughly 50,000 named spider species, 2,200 named scorpion species and 900 named tick species worldwide.

Mites have evolved to live in almost every habitat on Earth, including:

• Topsoil and leaf litter (most species)
• Household dust (house dust mites)
• On animal hosts (bird mites, mange mites, ticks)
• Human eyelashes and hair follicles (commensal, harmless species)
• Freshwater and deep ocean hydrothermal vents
• Stored food products (flour mites, grain mites)

The vast majority of mite species are completely harmless to humans, pets and homes. Only around 100 species globally are considered structural or medical pests, with less than 10 regularly causing issues for Sydney households.

Frequently Asked Questions About Arachnids in Sydney

Are ticks really just a type of mite?

Yes, scientifically speaking. Ticks are a specialized subset of the Acari arachnid subclass, meaning they evolved from mite ancestors around 120 million years ago to become exclusive blood-feeding parasites. All ticks are mites, but not all mites are ticks.

What arachnids are most commonly found in Sydney homes?

The most frequent pest arachnids in Greater Sydney are redback spiders (found under outdoor furniture, in letterboxes and sheds), bird mites (common after birds nest in roof cavities), and white-tailed spiders. Paralysis ticks are common on properties adjacent to bushland, while scorpions are extremely rare in built-up suburban areas.

Can all arachnids bite or sting humans?

No. The vast majority of arachnids (almost all mites, most small spiders) have mouthparts too small or weak to pierce human skin. Only a tiny number of Sydney species pose a risk: redback spiders (venomous bite), paralysis ticks (toxic saliva) and very occasional large scorpions (mild, painful sting).

What’s the fastest way to tell a pest arachnid apart from a harmless insect?

Count the legs first, from a safe distance. 6 legs = insect; 8 legs = arachnid. If it has long, thin antennae or visible wings, it is definitely not an arachnid, no matter its shape or size.