Biology of Stinging Hymenoptera

Wasps and bees of all kinds have been organized into the Hymenoptera genus. Hymenoptera is defined in the 2002 Britannica Ready Reference as, "highly specialized insects with complete metamorphosis that include the bees, wasps, ants, ichneumon flies, sawflies, gall wasps, and related forms, often associate in large colonies with complex social organization, and have usually four membranous wings and the abdomen generally borne on a slender pedicel." Basically, these insects are a part of a large division of the insect kingdom, but the ones we are focusing on are the stinging sort: Paper Wasps, Yellow Jackets, Bumble Bees, bald-faced Hornets and Mud Daubers. Each of these Hymenopterans will be described in detail below.

Common Wasps and Bees in the Northwest

Paper Wasps
Paper Wasps are non-aggressive Hymenopterans. They are social and their nests are not as large in size or number as Yellow Jackets. The Paper Wasp is larger than the Yellow Jacket, usually about 1½ inch long having two longer, skinnier, body sections, two pairs of wings, and are yellow with black stripes. Their nests usually are home to 5-20 wasps. They do sting, but usually will not pursue or sting a human - even if the nest has been disturbed. Paper wasps are rarely a nuisance to people unless a person has an allergic reaction to insect venom. If you are a person with such allergies, it is necessary to take every precaution and rid your home or place of business of all stinging insects and spiders.

Yellow Jackets
Yellow Jackets are some of the most aggressive Hymenopterans. They are social insects, organized inside the nests into castes that consist of a queen, drone and workers. A common worker will be about one inch in length and is yellow with black stripes. In the Northwest their nests can range in number from 20 in the early stages all the way into the hundreds depending on the local environment. Yellow Jackets do sting, inject venom, and are very protective of their nests. However, they usually will not attack unless the nest is being encroached upon.

They are scavengers and will eat most anything. You may have experienced them intruding on your Barbeque late in the summer when their nests have grown to peak size and food sources are more scarce. If you were to watch the foraging worker Yellow Jackets, you would see that they are indiscriminate about their food sources. Yellow Jackets will eat meat, sweets, starches; pretty much anything edible.

One reason to be thankful for the fall is because during the temperature change the queen is the only yellow jacket that will survive.

Their nests are often in wall voids, attic/crawl spaces and abandoned rodent burrows in the ground. Their nests consist mostly of wafer-type egg cells. As mentioned earlier, the common places for Yellow Jacket nests are enclosed places, however if the nest is not enclosed on all sides, they will build exterior walls of fiber/saliva materials.

Bumblebees
Bumblebees are also non-aggressive, social Hymenopteran. Bumblebees are social with small nests that usually are less than 50 in number. Except for the queen, all bees in the nest will die at the end of the season. Bumblebees can sting, however they are very unlikely stingers. The affect of their sting varies based upon the victim. Bumblebees do not fly with great finesse or accuracy. They are able to get from point A to B, but are clumsy and slow. They are the second largest contributors to the pollination of wild flowers after Honey bees. They are a crucial part of our environment and should not be killed except under extenuating circumstances such as a person having insect venom allergies.

Bumblebees make their nests out of grasses, insulation, and other dry materials that are small enough to be chewed and carried by the insects. The queens will set up nests in old rodent burrows, tree stumps, and wall voids. Bumblebees are large insects ranging from about 1 to 1½ inches and their flight produces a very startling buzz that is much deeper and louder than other common flying insects. Remember that despite their formidable size and sound they are not prone to stinging people.

Bald-Faced Hornets
Bald-Faced hornets are large and can be aggressive. They are black in color and range from 1 to 1½ inches long. Bald-Faced hornets are much thicker in stature than Paper Wasps and have two body sections with one pair of wings. These hornets are considered to be not quite as aggressive or difficult to control as Yellow Jackets, but they are still regarded as dangerous due to the size of the insect and relatively more intrusive sting.

A Bald-Faced Hornet nest will typically be in a tree or shrub and be a classic, oval shape. The nests are made of paper (a solution of insect saliva and chewed material) and have several tiers of eggs inside. These nests are usually about the size of a basketball by the time they are noticed by anyone and are likely to be found in rhododendron bushes. The entry/exit hole is usually at the apex and usually at the bottom of the nest structure. There are usually between 60 to 100 hornets in a nest the size of a basketball.

Mud Daubers
Mud Daubers are fairly common in parts of the Nortwest. They are solitary (they do not live in colonies), non-aggressive and look sort of like Paper Wasps in their basic body structure. Like Paper Wasps, Mud Daubers have two body sections, but they also have a long, string-like waist section that distinguishes them from Paper Wasps. They come in many different colors, but are usually black and yellow.

Control Measures

Wasps and Bees are relatively easy to control in large part due to their acute reaction to pesticides and because we are able to treat wasps at the site of their nests. Locating the nest is the first step toward control. The second is introducing a pesticide into the nest which, of course, is a lot easier said than done!