Whenever an insect lands on you, it is time to pay attention and figure out if there is going to be a problem! Is there going to be a bite or sting or just a tickle with no further consequences?
I recently noticed a scary-looking small bug on my leg while biking and decided to check this out since it strongly resembled one of our most feared wasps, the yellow jacket. Now yellow jackets are not to be trifled with as I have learned several times when I have had to deal with their formidable nests. They are fierce and have a strong sting and an attitude to boot. On closer inspection I realized that although this bug (see photo of syrphid fly) is a close mimic of the yellow jacket wasp, it is in fact a fly. How did I figure that out? I look at the wings and can see that there is only one pair of wings (wasps have two which fold back). The eyes in flies are larger and placed differently and the antennae are shorter. If you can see the mouth, flies have sucking or piercing mouth-parts whereas wasps have chewing mouth-parts. Flies also behave somewhat differently – for example this bug was drinking sweat from my leg- in an apparent attempt to pick up some salt/sodium which is lacking in their mostly herbivorous diet. With some practice you will be able to make this distinction too, so do not just dismiss the swarm of bugs flying around you in Summer-time, have a look at them carefully and pick out the pretenders from the real bad dudes.
Now just when you have the flies separated from the wasps, along comes another yellow and black critter (see photo of locust beetle) which is not uncommon in our yard since we have a lot of black locust trees. This is an entirely different type of insect (a beetle instead of a fly or wasp), yet it is colored rather similarly and seems to be also mimicking a yellow jacket to obtain protection from predators. Birds likely recognize and avoid yellow jackets and their mimics which fosters the evolution of such convergence in color and pattern. This does not work on mammals such as skunks which make a good living by digging out and eating the young found in the nests of yellow jackets. Indeed skunks, which themselves are well protected by scent and advertised by a striking color, are highly thought of in our neighborhood by farmers who value them for their ability to destroy yellow jacket nests which can cause a lot of pain during haying time.
So learning the basics of insect identification can pay dividends not only in terms of protecting your own hide, but will add to your understanding of and enjoyment of the natural world.
Bill Dunson, Englewood, FL & Galax, VA