Stirring up a Hornets Nest
Is getting stung on occasion by wasps just the price one has to pay when venturing off the path to pick wild berries or cut firewood? The hot dry weather we’ve had this July seems to be favourable for the buildup of wasp colonies and that’s a pretty good sign there will be uninvited visitors at August and September picnics and barbeques.
The group of wasps which can be a nuisance are social wasps in the family Vespidae. The vast majority of wasp species pose no threat to humans and wasps in general are important predators of insects. They masticate and then feed a huge number of flies, caterpillars and other insects to the developing larvae. (The adults mostly consume high sugar foods like nectar and ripe fruit.)
The ability of the various wasp species to manage their thoracic temperatures has implication on their food gathering abilities. Hornets can raise their body temperatures higher than can yellowjackets and can thus hunt earlier in the morning at cooler temperatures. Much of their insect prey is not very active at cool temperatures so hunting live insects is easier. Yellowjackets cannot raise their temperatures as well and the consequence is evident in their habit of feeding primary on dead insects (and also meat at picnics and barbeques).
Hornets typically prey on live insects. Their beneficial role in maintaining insect populations, makes it seems desirable that when possible, we find a way to get along. The challenge for humans with the Vespid wasps which includes the paper wasp, yellowjackets and hornets is that because of their colonial nature they defend their homes and sometimes those homes are where we want to be. And the stings, which can be applied multiple times hurt!
Paper wasps build small open paper combs which to my eye look unfinished and typically have fewer than 100 individuals in a colony. I usually find these under the eaves of the house. Yellowjackets make their nests underground. Hornets have enclosed paper nests. By late summer their numbers will be several hundred in a nest.
Despite the behavioral differences between wasps, yellowjackets, and hornets they all use wood fibres to make the paper for the nests. It is pretty interesting to watch (and listen to) a wasp scraping wood fibers off of old boards, fence posts, cedar siding or tree bark. These nests are started in the spring by the queen. The eggs hatch into worker females that then take over nest building and hunting or gathering of high protein foods like meat (ie insects) or plant pollen which is also high in protein to feed the developing colony. The queen continues to lay fertilized eggs which develop into more female workers and so the colony builds. In the late summer she lays unfertilized eggs which develop into males as well as fertilized eggs into larger cells which develop into new queens. The old queen dies in the fall and the new queens mate and then spend the winter in a sheltered places. Only the mated queen survives the winter.
The wasps which are a nuisance at fall picnics (and when picking fruit) are typically looking for high sugar foods for themselves, since there are no new larvae developing. When they have larvae to feed they are still focused on the high protein foods.
In spite of the pain and nuisance wasps may at times cause us we would do well to try and live with wasps because of their ecological importance.
Behavioral Differences Between Wasps, Yellowjackets, and Hornets at take5.ca
Behavioral Differences Between Wasps, Yellowjackets, and Hornets
|Type of Nest||Open, umbrella-shaped paper comb||Enclosed paper comb||Enclosed paper comb|
|Nest Location||Often under eaves or in other protected locations||Usually underground in old rodent burrows||Often on trees or shrubs|
|Size of Colony||Usually less than 100||More than 100||More than 100|
|Feeding Habits||Preys on live insects||dead insects, sugars||Preys on live insects|
Jay Rastogi is a naturalist and educator in Yellow Point. You can reach him at ecoforestry [at] gmail [dot] com