Some thoughts from my friend Greg Boyd:

I’m preaching through the book of Luke these days (actually the last several years), and this last week was on Luke 10:17-24. In this passage the 70 disciples that had been sent out by Jesus returned and were joyful because they were able to cast demons out of people. Jesus responded, “I saw Satan fall like lightning from heaven.” He then adds, “I have given you authority to trample on snakes and scorpions and to overcome all the power of the enemy…” (vs.18-19).
I find it interesting that snakes and scorpions seem to be grouped in the same category as “the power of the enemy.” This in turn suggests that these creatures are not entirely the handiwork of the all-good, benevolent Creator. If the creation hadn’t been corrupted by the “god of this age” (2 Cor 4:4) and “principality and power of the air” (Eph 2:2), it seems these creatures would look and behave very differently from the ways they now look and behave (by the way, my paparazzi messy-room hater lard friend Marcia was stung by a scorpion in Costa Rica last year…and she would definititely attest to the demonic nature of scorpions).
If this line of reasoning is correct, this passage lends further support to my Satan in Nature (S.I.N.) hypothesis. Nature itself has been corrupted by Satan and the rebel Powers. God’s beautiful creativity is still present throughout nature, but it’s also resisted by the destructive forces of rebel spirits. So everything that has evolved reflects God’s handiwork but also contains some element of Satan’s corrupting influence. This, I argue, is why the animal kingdom is so full of violence – despite the fact that God originally created the world entirely free of violence, according to Genesis 1 (vs. 30). It also in part explains why nature often acts in massively destructive ways.
The one who holds the power of death (Heb 2:14) together with his minions has corrupted God’s good creation. But someday, praise God, the entire creation will be redeemed. Lions shall lay down with lambs, and snakes and scorpions will play with mice.