(NBC)  If your pet is pawing at the door for one last romp in the grass, it's important to make sure they are still protected from pests like fleas and ticks.  

That's doubly important this time of year, when domestic animals can act as transportation for critters wanting to come in from the cold.

Dr. Stan schneider, a biologist at the University of North Carolina at Charlotte, says pests like fleas and ticks are looking to stay warm too.

"It may be winter outside but inside our houses we're maintaining a constant sub-tropical condition."

Dr. Stan schneider studies insects for a living. He says that cold weather now moving into more of the country can kill off pests, but it takes longer than many people think.

"It takes several days of consistent sub-freezing weather to kill off adult fleas and their larvae." says Schneider  

So now is not the time to stop applying the medications that protect your pets from fleas and ticks. Treatments many associate with warmer months.

Your vet will thank you, you pet will thank you, and before too long your holiday guests may thank you too!