The garden-variety tick is not much in size, but as a disease-carrier, it packs a punch.

The deer tick is a notorious example.

Also known as the black-legged tick, the carnivorous little bug is barely a speck on the body when it quietly chomps through skin and burrows in for a good, long drink.

It is extremely stealthy and can feed unnoticed for days, usually doing little harm to its host. But it can transmit dangerous parasites.

Then trouble starts.

The main reason deer ticks are noticed at all is because they are a leading purveyor of Lyme disease, which causes a trademark bulls-eye rash and, if untreated, neurological damage.

Scientists haven’t yet turned the tables on these disease-carrying ticks, but they are learning something from the little arachnid’s ability to sup on its host for days.

The trick is in the spit.

When a tick clamps down, it breaks through tiny circulatory vessels that spill blood.

Normally human blood would clot and interrupt the tick’s lunch, but a compound in tick saliva blocks three natural clotting factors that until now have been mysterious.

Researchers at the University of Amsterdam in the Netherlands found a protein that inhibits activation of “Factor Five,” a protein that many families become familiar with because it is linked to hereditary clotting problems.

Currently, warfarin is one of the most widely prescribed medications for patients battling heart disease and other clotting ailments, but its effectiveness depends on a person’s genetic make-up.

The new discovery provides understanding on how clots form, how anticlotting drugs work, and how new blood thinners could be developed.

It’s not payback for health problems caused by pestering ticks, but it could be considered consolation.

Call it a little bit of “tick” for tat.