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Basic Facts About Commonly Encountered Insects
Insects are a large and diverse group of organisms that move between locations under their own power. All insects are considered animals and they actually comprise about 75% of this group. Mollusks (clams & snails) comprise the next largest category of animals. All other creatures like birds, reptiles, fish, and mammals comprise only a very small portion of the animal population on our planet. Worldwide, about 1 million species of insects have been identified
Almost all insects posses the ability of flight. Forty million years before birds took to the air, insects were flying. The fossil record shows that large, temperate swamps existed at this time which provided a food source for oceanic creatures coming to land. Some of these became trapped in plant rosins which fossilized to amber. From this we can obtain some idea of how insects developed. Few predators existed at first, but insects retained small flaps that resulted from the evolution of gills to lungs. As competition began to increase, these flaps aided in jumping away from predators. By natural selection, the size of these flaps eventually increased to the point of becoming wings. Fossils of dragon flies from this period indicate wingspans of up to one yard. A portion of the dragon fly’s wing actually enters its body and results in almost bird like flight. The limitation to this however, is that a insect can only flap its wings twenty times per second. In order to overcome this, other insects attach muscles to the top plate of their thorax. This is then pulled tight like a guitar string. Other muscles tweak the string muscle and the resulting vibration moves the wings very rapidly. The frequency of vibration depends upon the size of the insects body cavity. It can be heard as a high whining noise in mosquitoes or as a low buzz in bumble bees. A bee keeper can check the sound of his hive to see what condition it is in, 880 Hz would indicate health
Other natural defenses that insects use to avoid predators may be as simple as body chemicals. Stink bugs, for example, release substances that repulse other animals in a threatening encounter. Monarch butterflies feed on milkweed, a plant with very bitter sap. This causes them to taste quite awful to birds or other predators and thus their markings become recognized and they are left alone. The Viceroy butterfly has taken advantage of this fact by copying the Monarchs color scheme. This defense is called mimicry. Camouflage may be used as in the walking stick which looks like a twig or other cryptic color patterns may be used as in the case of the Pepper moth. Prior to the 1860’s this moth existed in England with numerous black and white spots. Layers of soot from the industrial revolution destroyed their camouflage pattern so that only those with more dark speckles survived. After England began cleaning up its environment the Pepper moth reverted to its regular state. Alarm coloration is yet another defense that uses fast color change or a pattern change to startle away predators. An example would be the owl moth, which can make itself appear to have large eyes and cause a bird to think it is in danger of attack
The variety of insects is greatest in regions around the equator, however, the highest number of insects exists further north. This is due to the fact that biomass is very low in the tropics. The head of these creatures contains a brain that allows it to react to an environment by instinct, but it can not actually think about things. Every insect has three basic activities; this includes eating, finding a home,and mating. Most insects have very good cutting mouth parts and can cause considerable loss to world food supplies. About 1/3 of all the worlds grain is eaten by insects and approximately 50% of all fruit is lost in the same manner. This is with the use of pesticides! The very first pesticide to be used was powdered clay. The fine particles scratched the pests to death as they moved throughout a container of grain. Insects do benefit us through pollination. Shortly after insects appeared on the earth, flowering plants began to develop. Since that time, the existence of plants and insects has been co-evolutionary. Habitat along with mating and development vary greatly by which order an insect belongs to. All of these creatures experience a metamorphosis of change. This includes a larval stage which molts through several instars or a nymph stage that resembles an adult and gradually metamorphoses to sexual maturity. All true insects are Arthropods (meaning they posses six legs). To better understand insects, they have been placed into large groups with similar characteristics; these are called orders. The following are characteristics of insect orders most commonly encountered
Coleoptera
This order represents the beetles and the term means "hidden wing". The front wings of this group have been modified into hard covers that protect two thin and folded rear wings. Members can weigh up to 1/4 pound and still be capable of flight. They spend most of the time hiding. Examples would include Fireflies, June bugs and Wood borers
Dermoptera
Members mostly feed on plant pollen. They have vestigial wings which are being lost through evolution. Earwigs are representative. This name was derived from a false legend that they burrow into the brain through a persons ear.
Diptera
This group contains the flies. They posses two wings for flight and the two hind wings have developed into knobs called halteres. These halteres act like gyroscopes which allow the insects to make great maneuvers in flight. They may have daubing mouth parts, as with the house fly, that are 1000 times more sensitive to taste than our own. This can allow them to distinguish up to ten different types of sugars. Most diptera are parasitic and carry diseases in or on their bodies. Mosquitoes, Craneflies, and Midges are also part of this order
Ephemeroptera
Adult stages of this group exist only to reproduce and do not eat. Therefore, they tend to have very fatty, oily bodies for energy reserve. This has been known to cause problems on roads when large emergences of the insect occur and rest on streets causing slick conditions. They are an important food source for fish. The best example of this order is the Mayfly
Hemiptera
These are technically known as true bugs. When the wings are folded, a distinct X or hourglass pattern can be noticed on the back. Most of this group has sucking mouth parts and feeds on plants. Stink bugs and Bed bugs are members of this order
Homoptera
This order is refereed to as false bugs in that they are similar to Hemiptera, but the wings do not exhibit an X pattern when folded. The Cicatid is found in this order. Cicatid grubs may spend 1 to 17 years in the ground. When the adults emerge, they spend a day or so vibrating their abdomen to attract a mate, causing a familiar high buzz on late summer afternoons. After mating, the female lays her eggs in a twig, killing it, so that it falls to the ground where grubs burrow in and repeat the cycle
Hymenoptera
Included here are ants, wasps, and most importantly the bees. The coexistence of man with honey bees dates back as far as 10,000 years as evidenced by archeological artifacts. These insects benefit us through pollination of crops, production of honey, and wax. More deaths occur every year from bee stings as opposed to any other type of animal bite. The stinger is actually a modified egg depositor, therefore only female bees can sting. Once this happens the insect will die because tiny barbs on the stinger anchor it into the victim and it tears apart the insects abdomen afterwards. These bites can have an additive effect over time however and cause natural antibodies to build up in some individuals to the point where just one bite causes anaphylactic shock (increased heart rate, flushed appearance, respiratory distress) and immediate treatment with epinephrine is necessary. Bees are social insects. In a honey bee society, there are a queen, workers, and drones; how they are raised and the roles they have are quite different. A queen is produced by the type of food provided to her cell, by the other bees, in her formative stages. The queen will produce up to 300,000 eggs in her lifetime and creates the hive upon mating with a drone. The queen constantly emits a pheromone to the entire hive. As she becomes older, the production of this substance drops off and the hive uses this as a signal to create more queen cells. The queen may become competitive and sting these new queen larvae in order to kill them. If conditions in or around the hive become unfavorable, the queen may emit an overdose of this pheromone. In this instance the hive will become very docile and follow the queen in a swarm to look for a new home. The queen is rarely seen, but is recognizable by her large abdomen. Drones can be recognized by their very narrow abdomen and are most often seen in the fall. Drone bees are kicked out of the hive over the winter months. Worker bees are seen everyday and are responsible for food gathering for the hive and subsequent pollination of plants. It is possible that all queens may die in a hive and in this event it has been shown that the worker bee will become sexually mature
Not only do bees communicate social status they have demonstrated this ability in food gathering also. Entomologist Karl Van Frisch conducted an experiment in which a pot of honey was set out next to a hive. When a worker arrived at it he marked it with lacquer and observed it when it returned to the hive. First the bee made a "round dance" which told the other bees to go out and look for honey. If the honey was farther away the bee would make a figure 8 or "waggle dance" indicating the direction of the sun and distance to the honey. He also believed bee dialects existed and demonstrated their ability to recognize landmarks. Bees do not hibernate over the winter so the insects constantly move from the inside of the hive to the outside and use body heat to survive
Bee farming is a major business in the United States. Certain crops like Blue berries must be pollinated by bees, therefore, most Blue berry farmers are also bee farmers. Introduction of the African bee has been very costly to this country. This species is far more aggressive and contamination of existing hives has been shown to affect honey yields
Lepidoptera
This order includes the butterflies and moths. They can be distinguished from each other by the fact that moths hold their wings flat while resting where butterflies hold their wings up at rest. The adult stage of this order does not eat much, but the larval or caterpillar stage eats voraciously and is very disruptive to people. Gypsy moths and Red Oak moths are examples of this. They both tend to run in ten year population cycles. Where as the Red Oak moth does inflict damage at its population peak; it does not tend to completely denude and kill a forest as does the Gypsy moth. Much effort has been made to control the Gypsy moth in areas like Pennsylvania where the state was completely de-forested at one point
Nueroptera
These are known as lace wings or nerve wings because of large transparent wings crossed by many veins. They are found at a forest edge. The larval stage of this insect is known as a spittle bug and can be observed as a white foam in the branches of weeds. These insects are generally poor fliers
Odanata
Dragonflies and Damselflies belong to this order. They are very swift fliers that have been clocked at up to 20 mph and can change direction quite rapidly. Dragonflies are predatory on other insects, consuming their prey in flight. One Dragonfly can eat up to 1000 mosquitoes per day! Damselfies tend to feed on vegetation. This order is very sensitive to pollution
Orthoptera
Grasshoppers, Praying Mantis, and Cockroaches represent this order. Where Grasshoppers are very destructive to crops, Praying Mantis are very beneficial in controlling other insects. The concept that Cockroaches spread disease is largely false! The most common roach in northern cities is the German Brown Cockroach. In more southern climates, wild roaches are known as Palmetto Bugs
Placoptera
This order spends its life in cool running streams. They have adapted for holding on to rocks with claws and suckers and can spend one to two seasons on the bottom. When there is a large emergence of adults in the summer, it indicates a very good time to go fishing. The group is represented by the Stonefly
Trichoptera
This group also spends its time is fast running, cool waters. It is represented by the Caddis Fly. The larval stage of this insect is unique in that it builds very precise cases out of twigs for protection.
Siphonoptera
The fleas are most troublesome to pets and other animals. It should be noted that they can transmit disease to humans. Bubonic plague, which killed about 2/3 of Europe in the middle ages, was transmitted by rat fleas.
Mosquitoes
Pass through four distinct life stages which are egg, larva, pupae, and adult. The larval and pupal stages require the presence of water. Larvae pass through four sub stages known as instars. Which instar is present can be determined approximately by the size of the larvae. It is most preferable to larvicide in the 1st to 3rd instar stage because 4th instar larvae and pupae do not feed and, therefore, will not ingest a larvicide. Adult mosquitoes exhibit many different characteristics depending on what species they belong to. Generally, adults become most active at sunset and sunrise when temperatures do not fall below the mid 50 degree level. Some species will bite throughout the night or at any time of day. Only female mosquitoes bite animals, males feed on plant juices. The female mosquito bites to obtain blood which is processed through her body in the making of eggs. This is how diseases are transmitted from one source to another. An average life span for an adult mosquito is 20 days, however, some species over winter as adults in buildings or sheltered areas and these are often the first to be seen in the spring. Mosquitoes will take advantage of any conceivable source of water to breed in. This could range from tree holes to soda cans and is not just limited to swamps! The only requirement is that the object hold water long enough for the aquatic stage of the life cycle to be completed.
Quality Control
Involves surveying breeding sites and periodically revisiting areas to measure treatment effectiveness. ULV equipment that is used to treat adult mosquitoes is also calibrated by biology staff. These devices produce a non thermal aerosol cloud that consists of millions of microscopic droplets. These droplets must physically impinge upon the mosquitoes to be effective. The size of these droplets is determinted by the insecticide being utilized. The size of the droplets are determinted by the manufacturer of the insecticide and are specifically designed to target mosquitoes, while having less effect against larger insects such as bees when used according to the label and industry standard practices.