The frost-free spring and the high temperatures this summer were the perfect conditions for a bad wasp year.
I knew by mid-April that we would need to stock up on wasp spray at work, so I bought a case of 12 cans in preparation. My staff and I manage farm machinery and equipment sheds and regularly encounter hordes of stinging insects throughout the growing season.
This year, we saw wasps building nests in the last week of April. By mid-June, all 12 cans of wasp spray were depleted and I had to buy another case of spray.
I have received several email inquiries and office calls about how to control these guys this year — more than I can ever remember. My short answer to why wasps seem more plentiful this year is simply higher ambient air temperatures.
Most insects emerge from their winter slumber by degree days, which are a measurement of daily highs and lows, starting on Jan. 1 each year. Farmers and horticulture professionals use these numbers to determine when a particular insect will come out of winter hibernation. This valuable number allows us to know when to start a control for insects before they get out of control and kill high-value food and bedding crops.
A warmer winter and spring gives new female wasps more time to establish a bigger colony, which gives us more wasps to deal with earlier in the season, and a potentially more aggressive colony in late summer.
Now the stinging truth about wasps you may not know. Every wasp you see is extremely important to our ecosystem, so much so that I personally hate to spray or smash a nest. Unfortunately, wasps love to nest in man-made structures.
Wasps are either parasitic or predatory toward other insects. The whole reason they have stingers is to hunt food and lay eggs, not really for the defense of their nest site.
Parasitic wasps, like Encarsia formosa, lay an egg in the back of a unsuspecting aphid. The egg hatches and eats the plant-sucking aphid from the inside out before emerging as a new adult wasp. These wasps are very small, solitary insects that pose no threat to human safety.
Predatory wasps — which kill and eat other insects or use them as a host to lay eggs on — are the ones most of us encounter, like black or red wasps, yellow jackets, hornets and, my favorite wasp in our region, the great cicada killer.
Most of these wasps like sugary foods, which is why you see so many flying around your summer cookouts. They become more aggressive in the shorter days in the late summer, and their nests are extremely dangerous to be around.
If the nest is up high on a structure or out of the way of your summer activities, leave it alone and let the wasps have some space. If you must destroy the nest, make sure to do it early on in the season, in May or June, before it gets big.
Also, you can purchase fake nests to hang around your deck, outbuildings and homes to deter them from making a real nest. Most wasps are territorial up to 30 to 50 feet and will not build a nest if one is already present.
If you have a yellow jacket nest on your property, I would highly recommend destroying it. Yellow jackets are by far the most aggressive insect we have around here. They will chase you or anything they deem a threat for over a hundred yards once disturbed. Plus, late-season nests can contain thousands of yellow jackets, making for a life-threatening situation for people and pets.
Again, if the nest site is out of the way, try and leave it alone. Wasps will make a new nest each year and rarely use the same nest after one season.