Common Name: Assassin Bug
Scientific Name (Family): Reduviidae
(Information for this species pages was gathered in part by Nathan Hand for Biology 220W at Penn State New Kensington in Spring 2013)
Assassin bugs are members of the extensive taxonomic family Reduviidae (Class Insecta, Order Hemiptera). This is a very large family of Hemipterans that contains more than seven thousand individual species. Assassin bugs are found all over the world, and there are one hundred and fifty nine species in North America.
Adult assassin bugs range in size from four millimeters up to 40 millimeters (about an eighth of inch to an inch and a half). Most species are predators of other insects and arachnids (especially spiders), but some species feed on blood taken from a variety of vertebrate hosts. Some predatory species of assassin bugs are highly specialized and take only one type of insect or arachnid prey. Other species are much more generalized in their prey preferences and selections.
Image credit: B. Stock, Wikimedia Commons
“Kissing bugs” (Triatoma sp.) are a blood feeding group of assassin bug that prey on humans, These assassin bugs are capable of carrying and transmitting the trypanosome protist parasite that causes Chaga’s Disease. These “kissing bugs” feed on humans at night especially around the eyes and mouth and deposit trypanosome-rich feces near the spot of the bite wound. Scratching at the wound can then mix the feces into the victim’s blood and infect the individual with the disease causing trypanosome. It is estimated that seven to eight million people in Mexico, Central and South America have Chaga’s Disease, and that it causes almost thirteen thousand deaths each year.
Assassin bugs have elongated heads with narrow neck-like stalks that attach to their thoraxes. They have long legs, large triangular heads, and long, tubular mouthparts (the “rostrum”) that wraps under their head and neck. They are usually brightly colored with red, orange, brown, and black fields and patterns. Their front legs in particular may be highly expanded to grasp prey. Their legs may also have tiny hairs and even sticky secretions which help them hold onto their captured prey. The tubular mouthparts are the essential characteristic of hemipterans (“true bugs”). In the assassin bugs this beak-like structure formed from their mandibles and maxillae is hard and sharp and is used to repeatedly stab into the body of their prey (hence the common name “assassin”). The salivary secretions ejected through the rostrum have not only digestive enzymes (which enable the assassin bug to externally digest their prey and then suck up the pre-digested, nutrient rich juices), but also anti-bacterial chemicals and insecticidal venoms designed to disable or kill their prey.
Assassin bugs are considered to be important bio-control agents especially in organic (i.e. not pesticide managed) agro-ecosystems. They prey on aphids, caterpillars and even insects as large as cockroaches. They may lure prey via chemical scents and pheromones or via specific behaviors (like vibrating the webbing of a spider to draw the spider out of its refuge). “Ambush” assassin bugs sit on flowers and wait for any approaching insect to be drawn close enough to be grabbed, stabbed, and eaten. These ambush assassin bugs may even consume some of the flower nectar as a supplementary food source but require insect prey for their growth and development.
Mating and Reproduction
Mating occurs in the early summer with males approaching the females via ritualized behaviors that include jumping, antennae touching, and hesitant approaches to copulate. The males guard the females after copulation in order to protect the integrity of their transferred sperm. Females then lay their fertilized eggs in clusters on stems and leaves of a variety of plants. The eggs hatch into tiny versions of the adult assassin bug because, like all hemipterans, assassin bugs display simple metamorphosis. The immature life stages (the nymphs) are smaller, non-winged versions of the adults. The nymphs go through four to seven molts (depending on the species) before they finally reach adulthood. Adults, as inferred above, have wings and, in temperate climate zones like Western Pennsylvania, are the life stages that will overwinter. Adults can live two years in captivity, but it is not known how long they live in the wild.
Nymphal life stages also are predaceous, but they are also quite vulnerable to being taken as food by a variety of invertebrate and vertebrate predators. Many species of birds, rodents, spiders, praying mantises, and even larger assassin bugs readily consume assassin bug nymphs. These nymphs often cover themselves with debris from their environment (dirt, leaves, pieces of dead insects, etc.) in attempts to camouflage themselves to both hide from predators and more easily approach potential prey.