Frogs are a common enemy found only in the Jungle.
They are deceptively dangerous, given the speed, range and unpredictability of their movement, and should be treated with care. The regular blue Frogs are slightly less dangerous than their volatile red cousins.
When a frog sees the Spelunker, it attacks by jumping towards him. This can be tricky to deal with, as the height and length of a Frog's leap is variable and random - sometimes the Frog will jump directly at you, other times it will jump high in the air. Sometimes the trajectory will be somewhere in between.
In fact, Frogs may jump slightly further than they can see. This means that if you stray just inside a Frog's vision, trying to back away might simply move you directly into its path!
If you have to approach a Frog, you'll have to deal with the risk of its unpredictable jump towards you.
Trying to jump over or stomp on a frog will backfire if it chooses to take a high arcing jump, but attempting to run beneath it as it leaps may also be dangerous if it jumps straight forward.
Furthermore, compared to the the Mines, The Jungle has fewer small tunnels that can be used to corral the Frog's movement and funnel them towards your waiting whip.
If these means are not available, dispatching a problematic Frog will require quick reflexes and a little bit of luck. Frogs pause momentarily between jumps, therefore the best plan is often to avoid the Frog's first jump as best you can and then stomp or whip it while it is recovering. You will need to quickly discern the direction that the Frog is moving and get out of the way - Either by ducking or jumping, or even sprinting away.
It is also of note that the stacks of three gold bars can almost completely hide the frog if it is present in the same location as the treasure.