If you know what signs to look for when you meet a wasp, it’s easy to avoid being stung.
Have you ever been buzzed by a bee or a paper wasp? They dive bomb you, fly close to your face, even collide with you, but without stinging? Those were probably sentries for a nest, trying to keep danger away. Sentry wasps can be stationed 10 to 20 feet away from the nest they’re guarding, and circle back to it from time to time. These wasps are the ones you’re most likely to come into conflict with.
Yesterday, I went out looking for some pleasantly aggressive sentry wasps I had met earlier in the week. No luck – the day was too blustery, and all the sentries were huddled alongside the nest. Cold weather is a good time to pull down wasp nests, if you need to do so: fewer active defenders.
At the nest itself, you’re more likely to see a different set of behaviors than the sentry flight routine. If the wasps in the nest consider you a threat, they will turn to face you, will lower the front of their bodies, and may open their jaws at you. If there are many wasps present, they may pulse their abdomens in unison, indicating that they may sting if provoked.
Note the bend in its front elbows, the lowered chest, and the slight spread to its jaws.
Beyond this, certain individual wasps are more aggressive than others. In the European Paper Wasp (the primary wasp discussed last week), as well as many related species, there’s a wide range of face patterning even among close relatives.
European Paper Wasps with spottier faces are more likely to be aggressive than those with more uniformly pale faces. Generally, wasps with less dominant faces stay out of the way of wasps with more dominant face patterns. This seems to hold true for wasp-human interactions as well as wasp-wasp interactions. In the below picture, the European Paper Wasp with a spotted face pulsed its abdomen at me (a threat of stinging) while the pale-faced wasp did not.
Trego's Mountain Ear 
Very interesting post, thank you!
When wasps pulse their abdomens, is that aggressive? Or is it only when they crouch their upper body down and pulse that it is aggressive? I’m a bit confused because I’ve also heard that pulsing the abdomen is the wasp respirating. I have a lot of paper wasps in my garden with whom I’m trying to coexist. Thank you!
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