Scorpions and vipers
In the last five years of desert exploration and travel I have seen one scorpion and one horned viper. I have seen sand viper tracks but no sand vipers. Despite our massive aversion and fear of snakes and scorpions one is forced to conclude they are simply not that common. And both the scorpion, the viper and the viper tracks were all near places with vegetation or visited often by people. In remote, arid conditions you are unlikely to meet these creatures.
Cerastes cerastes - the horned viper is the most widespread deadly snake in Egypt. It prefers rocky areas such as those of the Eastern Desert - East of the Nile - to the more sandy places West of the Nile - if it exists in a sandy area it will be near some kind of vegetation such as a lone acacia or tamarisk bush. They like to lurk near lone trees to catch migrating birds. In very arid places it prefers loose soil to sand.
The sand viper - Cerastes vipera - does not lurk in the lovely arid dunes that are such fun to slide down - it prefers the vegetation dotted dunes close to such oases as Sitra and Nuwamisa on the stretch between Siwa and Bahariya. Sand vipers are less widespread than the horned viper (which sometimes occurs without horns) and are less tolerant of extreme aridity. Both are nocturnal and are more likely to be seen in summer than winter, when they semi-hibernate.
Scorpions, again, prefer rocky places and places where other invertebrates lurk. They leave a six legged track, a bit like a mountain bike track, that can be confused with the far commoner tracks of long legged beetles. My only scorpion was on a discarded eggbox on the Partridge Dunes - a very regularly visited set of dunes, in fact the closest dunes to Cairo. Caves- traditionally the haunt of scorpions or so we are lead to believe - contain more beetles I think. People regularly sleep in the Djara caves and I’ve never heard of a live scorpion being sighted there. The general rule is: in places with no vegetation and no soil you can be reasonably relaxed. If there is considerable vegetation and dunes, typically at a well or oasis, keep an eye open for possible sand vipers and their giveaway ‘sidewinder’ type tracks. In the Eastern desert and rocky places with some vegetation or soil watch out for horned vipers. The only one I ever saw was in the main tourist venue of Wadi Digla - five minutes from where I live - it was curled up being watched by a group of ten hikers, unperturbed and dangerous only if trodden on was my guess.