When you think of wasps, your first thoughts may well be of hostile, stinging insects. But of the many species of wasps found in Maine, few are aggressive. In fact, many aren’t even interested in humans at all.
Instead, wasps are far more likely to be a danger to other insects.
Often confused with hornets and bees, wasps belong to the same taxonomic family and also sting. But wasps are a different species with a distinctive body structure, according to Jim Dill, pest management specialist at University of Maine Cooperative Extension.
“It’s all in the anatomy,” Dill said. “Wasps have a narrow connector between their abdomen and the thorax.”
In Maine, there are wasps not much larger than the head of a pin and others that reach 3 inches in length. Depending on the specific wasp in question, they may be predatory hunters, parasitic or a combination of both. Different types of wasps may build homes out of mud, wood fiber or by digging holes in the ground.
According to Dill, most wasps are non-aggressive, solitary critters. In fact, some of the scariest looking wasps are among the least hostile.
To humans, at least.
But other insects are a whole different matter. Among the more frightening looking wasps in Maine are the American pelecinid and ichneumon wasps. These wasps are quite benign around people, but have a rather gruesome reproductive strategy. Females of each species lay their eggs inside the larvae of other insects. If that was not bad enough, when the wasp eggs hatch, they feed on the still living larval host.
As horrific as that may sound, Dill said, there is another wasp in Maine that goes even farther when it comes to laying eggs and making sure her babies have food — the golden digger wasp.
Golden digger wasps dig holes and tunnels in the ground where they hunt for grasshoppers, Dill said. When she finds one, she will sting it and inject a venom that paralyzes the grasshopper which she then drags back to her underground nest.
“Ground diggers will lay their eggs on the grasshopper so when they hatch, they consume this poor grasshopper that is paralyzed but still alive,” Dill said. “It’s disgusting, but it is beneficial.”
Grasshoppers are considered pests because they eat garden items like lettuce, carrots, beans, corn and onions. Golden digger wasps also help out gardeners because those underground nests they build help aerate soil which allows water and other nutrients to reach plant roots.
While the ichneumons, pelecinids and golden digger wasps are on the large size — up to 3 inches long — other parasitic wasps are so tiny you have to look hard to see them with the naked eye.
Some, Dill said, are so small they act as parasites on other parasites, a behavior called hyperparasitism.
“These tiny wasps usually parasitize other parasitic wasps,” Dill said. “It’s really amazing, the range of size and behaviors in the wasp family.”
The wasp that most people are familiar with, Dill said, is probably the paper wasp. They look very much like a bee, but they do have the distinctive thin connector between their head and abdomen. And also like bees, they are social with small colonies that have a queen and workers.
Paper wasps build distinctive nests out of a substance they make from wood fiber they chew up into a paper-like material. These nests look like upside down umbrellas with holes — or cells — on the bottom. Paper wasp colonies are very small, often with only 12 wasps in them, Dill said.
“These nests are on the small side and often you will see them under the eves of a house or other building,” Dill said. “It will look like someone stuck a honeycomb up there.”
Paper wasps are territorial and will defend their nest, so if they see you as a threat or if you disturb their nest, they will attack and sting you. The best way to avoid tangling with a paper wasp, according to Dill, is to avoid the nests.
“Paper wasp nests are usually in places where they don’t bother people,” Dill said. “But if they are, you can wait until after dark and take something and whack it down.”
Mud is another material used by some wasps in nest building, Dill said.
Some, like mason wasps, will look for holes in bricks and wood. The female will bring small caterpillars back to the hole, stuff them in and then lay her eggs. When she is done, she uses mud and sand to seal up the opening. When the eggs hatch, the larvae will feed on the caterpillar before breaking out of the sealed opening.
Instead of looking for existing holes for her nest, potter wasps construct little pot-like structures on the branches of trees. Those pots get filled with caterpillars before the queen lays her eggs and seals them up.
“You will often see mud dauber wasps flitting around mud puddles and flying off with bits of mud on their legs,” Dill said. “They take that mud back to their nesting site and pack it on until it’s the way they want it — they are really good engineers.”
Mud dauber nests are often found in the eaves of old buildings or high up on wooden beams.Those nests are a series of tubes built side-by-side that can be anywhere from 1 to 8 inches long, depending on the species.
A world without wasps, according to entomologists at the British Natural History Museum, would be a very different place. They have an important role in controlling numerous pests that threaten crops and gardens. Wasps eat a wide variety of insects.
“They really want to be left alone to do their things,” Dill said. “The biggest danger for getting stung is if one flies down your shirt or if you accidentally step on one.”