Polistes fuscatus

Polistes fuscatus occurs in temperate North America, from British Columbia east to the Atlantic, and south to West Virginia. (Evans, 1963; Milne, 1980)

Polistes fuscatus nests in woodlands and savannas. It is fairly common around human habitations, especially where exposed wood is present and can be used for nest material. (Evans, 1963; Milne, 1980)

The length of P. fuscatus ranges from 15 to 21 mm . These wasps are very slender and have a waist connecting the thorax and the abdomen. They are a dark reddish-brown color, and the body is segmented by yellow bands. Their pointed heads distinguish them from yellow jackets. In males, the tips of the antennae are strongly curved, and there is more yellow marking the front of the head.

Females of these wasps have a venomous sting. (Milne, 1980)

Polistes fuscatus queens lay fertilized eggs into individual cells within the nest. The larvae which subsequently hatch from these eggs are fed and protected by the queen and subordinate females until they are ready to pupate. The larvae are then covered with a silky covering. The first generation emerges from pupation as into smaller, infertile females. These are the true workers of the colony. Later in the life of the nest, males and fertile female offspring are produced. The fertile female offspring are the next generation of queens. They survive the winter and start new nests the following year. (Lyon and Wegner, 2001)

The lifespan of P. fuscatus is approximately one year, or the time it takes a queen to develop and to mate. Larvae from that are laid during the summer are well fed because of abundant food, and are capable of becoming queens. These eggs hatch before fall and the resulting offspring hibernate during fall and winter. The new queens emerge in the spring to begin nests and lay eggs. By fall, after laying eggs that will develop into new queens, these queens die. All accompanying workers and males die with the queen. (Evans, 1963; Unknown, 2001)

Polistes fuscatus is social and has complex societies based around a single queen. One fertile female begins building a nest after hibernating for the winter. Other fertile females begin working with her but the original female's dominance is accepted. Once the nest is built, the queen can drive the co-foundresses away or relegate them to worker status. These secondary females are still fertile, but the queen eats the eggs laid by these females as part of the assertion of her own dominance as the queen. The first offspring produced by the queen are infertile females who are not capable of becoming queens. These are the true workers as they do not pose a threat to the queen and can do nothing but build the nest and care for the young. Although a queen does lay eggs capable of becoming fertile females, she does so late in summer so that they can hibernate during winter and become queens or co-foundresses in the spring.

The division of labor in this species is related often to age. Younger wasps are somewhat pampered, receiving food and the paper used to build the nest, whereas older wasps have to forage for paper and feed the larvae. (Evans, 1963; Grzimek, 1972; Naug and Gadagkar, 1998)

As social wasps, P. fuscatus must have communication avenues for nest and hierarchy building and for defense. In order to establish dominance, a queen adopts a series of threatening postures that cause her underlings to subordinate themselves.

A chemical producing gland towards the posterior portion of the wasp produces a chemical that separates eggs laid by the queen from eggs laid by workers. The queen uses this chemical to decide which eggs to eat and which eggs to allow to grow.

Outsiders, even conspecifics, are not well-received in an existing nest and are quickly removed. As an outsider cannot be discerned visually or through tactile sensation, P. fuscatus relies on chemical cues. Pheromones are released by the wasps and the pheromones are specific to each nest. The specific chemicals are acquired upon birth by the wasps. It is extremely difficult for an individual to become accepted into a neighboring colony, unless it establishes a new colny of its own. (Evans, 1963; Gamboa et al., 1996; Turillazzi and West-Eberhard, 1996)

Adult P. fuscatus feed mainly on plant nectar. The species is considered insectivores because it kills caterpillars and other small insects in order to provide food for developing larvae. Foragers collect various prey insects to feed to the larvae. The wasp then malaxates, or softens the food and in doing so absorbs most of the liquid in the food. This solid portion is given to older larvae and the liquid is regurgitated to be fed to younger larvae. (Turillazzi and West-Eberhard, 1996)

Polistes fuscatus is eusocial but its social organization is not as rigorous as other eusocial organisms. Whereas in some other eusocial insects, guard polymorphs have developed that specialize in nest defense (e.g. soldier termites), paper wasps have only workers and queens. These two classes work together to fend off nest predators and parasites.

Two trends have been found in the study of anti-predator adaptions in P. fuscatus. The first is that the queen is the most aggressive defender of the nest and the second is that aggression in both workers and queens increases with the passage of time. These two adaptations reveal the incomplete eusocial nature of P. fuscatus. The queen is the most aggressive because she has a huge reproductive investment in the nest. The workers become more aggressive with time since their investment increases with time. (Evans, 1963; Judd, 2000)

Wasps feed on the nectar of plants and in doing so, they transfer pollen from one plant to another, aiding in plant reproduction. They are thus essential to ensure that plants reproduce. To the extent that these wasps fall prey to other animals, they affect the survival and reproduction of those predators. Polistes fuscatus also affects species upon which it preys in order to feed larvae. (Unknown, 2001)

Due to the proximity of the wasps to humans and their habitation in houses and other buildings, they can prove hazardous. They can inflict stings on domestic animals in places such as barns where they may have nests. Humans are also at risk of aggravating these insects and suffering from stings.

Polistes fuscatus feeds on various garden insects. The wasps feed on caterpillars and these insects also serve as major sources of food for the eggs. Organic gardeners benefit greatly from these wasps because they eliminate the need for pesticides. ("Organic Gardening", 1995; Unknown, 2001)

Polistes fuscatus is one of the most common wasps in North America and the one that is very well studied due to its steady population sizes, therefore there is no cause to worry about the status of this species.