[brunie's mom]

I found the info about how important the temperature must be for the heartworm to develop in the mosquito.

I just copy and pasted...because the info was on a breeder's website:

"Once the mosquito ingests the microfilariae from the infected dog, the larvae must go through two
stages of development, or molts, changing from L1 to L2 and from L2 to L3, while in the mosquitoe’s
system before the mosquito can infect another dog. Once the L3 stage has been reached the larvae
migrate to the mosquitoe’s mouth. It is only the L3 larvae which are capable of infecting another dog.
This mosquito cycle takes anywhere from two weeks to about a month depending on the weather. The
warmer the weather, the faster the development. If the larvae haven’t made the final development by
then, they never will because the mosquito dies of old age at about 35 days, and along with the
mosquito, die the larvae.
The importance of temperature: While the larvae are developing in the mosquito, development
continues only when the temperature is above 64 degrees F. Further, the temperature MUST remain
above 57 degrees Fahrenheit at all times, day and night during the entire mosquito cycle. If at any time
during the development into the L3 stage, the temperature drops below 57 F, the development is
aborted and must start over. Remember, it is only the L3 larvae which are capable of infesting your
dog.
Now let’s say that a mosquito has bitten an infested dog; and that the temperature has remained above
57 degrees F for a minimum of 14 days since that bite; and that the mosquito bites your dog.... "

So even if mosquitoes are seen in the snow...and the temps are cold...these mosquitoes cannot transmit heartworm.

Gina