Introduction

Invasive Species Defined

What's Being Done

 National Invasive Species Information Center

Submodule 4: Invasive Insects

Leading Problems

• Mediterranean fruit fly (Ceratitis capitata) – The Medfly, as it is commonly known, was first identified in the U.S. in 1929. It is detrimental to agricultural crops because the females lay eggs on developing fruit, which then serve as food for the developing larvae; damaged fruit is the result. The fly originated in African and spread north through the Mediterranean and southern Europe. It has now invaded most tropical and sub-tropical regions around the world. The Medfly is still established in Hawaii, but eradication efforts on the mainland U.S. have kept it from gaining a foothold. Federal and state officials are diligent in checking for the presence of the Medfly and in controlling its spread. Control efforts have included spraying insecticides, applying insecticides to soil where Medflies pupate, and releasing sterile males into a population.
  
  
• Africanized honeybee (Apis mellifera scutellata)–Africanized honeybees, or “killer bees” as they are sometimes known, were first identified in the U.S. in southern Texas in 1990. Since that time they have been found in Arizona and California, and may spread throughout the southern U.S. Interestingly, there are no native honeybees in the U.S. The bees we are familiar with in this country are European honeybees. In the mid-1900s, workers in Brazil set out to improve European honey bees by breeding them with an African variety that produced more honey. Some of these Africanized bees escaped and they have been spreading northward ever since. These Africanized bees and their hybrids are more aggressive than their European cousins and have caused several deaths from stinging by swarms of bees supposedly trying to protect their nests. Two methods of control are to expose queen bees to large numbers of European honey bee drones for breeding and to make sure the queen in a colony is of European descent.
  
  
• Emerald ash borer (Agrilus planipennis) – In southern Michigan, property owners began to notice decline and death in ash trees (Fraxinus spp.). In 2002, the cause of this phenomenon was identified as Emerald ash borer, which is native to China, Mongolia, Inner Mongolia, Korea, Japan, Taiwan and the Russian Far East. Since 2002, the insect has been found in Ontario, Indiana, and Ohio. By 2005, about 15,000 square miles in Michigan were infested. The borer damages and kills trees by feeding on the phloem and sapwood, mainly during its larval stage. Ash tree are ecologically important because their seed provides food for wildlife. In addition, ash is used for flooring, furniture, sports equipment, and other economically important products.
  
  
• European gypsy moth (Lymantria dispar) – in the mid-1800s, the gypsy moth was intentionally imported into U.S. for silk production. The idea was to find a moth that would hybridize with a silk-producing moth bringing immunity to diseases suffered by other moths. In Massachusetts, an experiment went awry with some moths being released into the wild in about 1869. Within a few years, neighborhood trees were defoliated by these accidentally released moths. Since this time, gypsy moths have damaged millions of acres of trees in the northeastern part of the U.S. Larvae have been known to travel many miles via wind currents which has allowed its spread throughout many parts of the country, even as far as the west coast. Caterpillars feed on tree foliage and kill these trees if defoliating the same tree year after year. Several control methods have been imposed including the introduction of viruses, insects, and fungi that destroy the moths. Methods of preventing larvae form reaching the foliage have been successful in saving trees as has the scraping off and burning of eggs masses from infested trees.
  
  
• Imported fire ants (Solenopsis invicta Buren, S. richteri Forel, and their hybrid) – Both of these ants, which are 1/8 to 1/4–inch long and reddish brown to black in color, were imported into the U.S. in the early 1900s from South America. Since this time, they have become established in the southern and western parts of the country. The sting of these ants inflicts a painful blister that can become infected. In addition, the sting can cause shock which can lead to death. Fire ants have been known to sting and kill young domestic animals. They also damage crops by eating seedlings of corn, soybeans, and other plants. Because they appear similar to native ants, they can be difficult to identify. Their characteristic mounds and aggressive behavior gives them away. Colonies can hold over 300,000 members and there can be several colonies found on a single acre of land. Spread of these ants is difficult to control because of their ability to fly at some stages of their lives, and because of the behavior of the colony to protect the queen. Baits containing insecticide or insect growth regulators that eventually make there way to the queen have been effective in controlling the spread of these ants.
  
  
• Silverleaf whitefly (Bemisia argentifolii) – It is estimated that the silverleaf whitefly has caused U.S. agriculture loses of over $500 million annually since 1991. Whiteflies feed on the sap of plants and commonly transmit plant-pathogenic geminiviruses from plant to plant. Now called honeydew, the sap exudes from the insect providing a growth medium for mold on the plant and subsequent damage. This species of whiltefly (there are several known to cause crop damage) is known to attack more than 500 different species of plant, causing major problems for tomatoes, members of the Cucurbit family, cotton, peanuts, and many others. Control of this pest includes attempting to breed geminivirus resistance into plants and the introduction of parasitic wasps into highly infested areas. In addition, there are species of fungi, spiders, mites, and other insects have been used as biological control.
  
  
• Asian tiger mosquito (Aedes albopictus) – The tiger mosquito, introduced into Hawaii in the early 1900s, was not found in the continental U.S. until its discovery in Houston in the mid-1980s. It is now found in almost 30 states. This mosquito is a known vector of several dangerous viruses including dengue fever and West Nile. It is thought to have entered this country in imported scrap tires from northern Asia. It is a nuisance biting insect with females taking blood meals during the day, unusual for most mosquito species. It breeds in standing water. Control measures include the use of DEET-containing insect repellent, removal or treatment of standing water, and adequate screens on housing.
  
  
• Cactus moth (Cactoblastis cactorum) – The cactus moth, native to South America, was originally introduced into some countries (not the U.S.) as biological control for prickly pear cacti (Opuntia). In the late 1950s it was introduced into the Caribbean and subsequently found its way to the Florida Keys. Since this time, the moth has been found along the Atlantic and Gulf coasts. Concern has arisen that the moth may severely decrease the prickly pear populations in these areas. Currently there is no good method of control available.