The INSECTS

ENTOMOLOGY - The scientific study of insects - Insects are the most common arthropod (exoskeleton) -Insects make up 75-78% of the animal species Insects are Vectors (organisms wh/ carry diseases) Ex. Malaria, Yellow Fever, etc.

-Exoskeleton: all insects have a skeleton on the outside

head abdomen thorax Insects have 3 body regions: 1. Head - Has 1 pair of antenna and mouth parts 2. Thorax - Has 3 pairs of walking legs (identify characteristic of insects) Also will have wings if they are present 3. Abdomen - May be further segmented head abdomen thorax

The small size of insects is of survival value to them HOW??? 1. Since they are small, they require small amounts of food to exist 2. Also, with their size they can easily hide from danger

compound eyes Insects have 3 PAIRS OF LEGS on the thoratic region - Some insects will have 1 or 2 pairs of wings (usually 2 pair) * Insects have a COMPOUND EYE

- Has many optical surfaces COMPOUND EYE: - Has many optical surfaces - Animal sees a mosaic or pattern of the object - Organisms with a compound eye have a huge visual field - There are many lenses (thousands of lenses) to detect movement - Compound eyes may be on an eye stalk where it can be moved around or these compound eyes may sit in an "orbital cavity" and be stationary

2. Nymph (juvenile) Stage 3. Adult Stage - Ex. Found in Grasshoppers METAMORPHOSIS - It is a dramatic change in form and function in the life cycle of an insect or animal - 2 Kinds: A. INCOMPLETE METAMORPHOSIS - The insect will undergo a gradual change in its appearence - 3 Stages: 1. Egg Stage 2. Nymph (juvenile) Stage 3. Adult Stage - Ex. Found in Grasshoppers

+ No wings are found on the organism during the nymph stage The nymph stage has the same appearence as the adult, but is somewhat smaller, less developed, and less complex + No wings are found on the organism during the nymph stage + Wings are found in the adult stage + Organisms in the nymph stage do NOT have the reproductive structures developed yet

COMPLETE METAMORPHOSIS: - 4 Stages: 1. Egg 2. Larva Stage 3. Pupa Stage (cocoon forms) 4. Adult Stage - Ex. Found in butterflies, moths, housefly, mosquito and beetles

+ In the pupa stage, the pupa are covered with a case or cocoon + In the larva stage, different types of insects are called different names: Caterpillars, Grubs, or Maggots + From the larva stage, the insect will go to the pupa stage which seems to be a resting stage but actually a lot of changes are taking place + In the pupa stage, the pupa are covered with a case or cocoon + Hormones will determine when the changes will occur

STRUCTURAL CHARACTERISTICS: A. Types of Mouth Parts found in Insects Insects have a variety of mouth parts This contributes to the success of the insects because they do not all feed on the same types of food Insects feed on a variety of food sources

2. PIERCING & SUCKING MOUTH PARTS: CHEWING MOUTH PARTS - Animals w/ these are likely to feed upon plant material such as leaves Ex. Grasshopper & Locust 2. PIERCING & SUCKING MOUTH PARTS: - These animals will feed on different food sources Ex. Mosquito sucks blood from its host chewing piercing/sucking

- The PROBOSCIS is used for feeding on the nectar found in flowers 3. LAPPING MOUTH PARTS: - An example of an insect wh/ has these is the housefly as it feeds on various food sources 4. SIPHONING MOUTH PARTS: - The insect will have a very long coiled structure called the PROBOSCIS - The PROBOSCIS is used for feeding on the nectar found in flowers

Types of Appendages in Insects: - WALKING LEGS & WINGS are used to provide the insect with locomotion & movement on the land, in the air, & in the water - The big development in insects is FLIGHT

C. Camouflage of Insects: CAMOUFLAGE - State that an organism will blend in w/ its environment & make it hard to see. This provides the organism w/ protection * Insects reproduce at a very high rate. A large number of these offspring do NOT survive - Since insects do reproduce in large numbers, this will assure that some of them will survive - Organisms wh/ reproduce in large numbers will have a low percentage of livability

BEHAVIORAL CHARACTERISTICS: - Insects exhibit a complex behavior - Insects have the ability to communicate - much communication depends on PHERMONES - PHERMONES - Are a form of hormone wh/ is secreted to the exterior & are used for communication w/ other insects. Ex. For reproduction

Order - Orthoptera ("straight-winged") THE GRASSHOPPER: Phylum - Arthropoda Class - Insecta Order - Orthoptera ("straight-winged") - Has an EXOSKELETON

head abdomen thorax 3 Regions: 1. Head Region - Contains 1 pair of antenna (sensitive to touch and smell) - Compound eye - Mouth Parts: LABRUM & LABIUM - Hold food MANDIBLE - Chew & crush food MAXILLA - Hold & cut food head abdomen thorax

spiracles 2.Thorax Region: A. PROTHORAX - 1st segment - Has head & 1st pair of walking legs B. MESOTHORAX - 2nd segment - Has 2nd pair of walking legs. Has 1st pair of wings. Contains SPIRACLES C. METATHORAX - 3rd segment - Has 3rd pair of walking legs wh/ are modified for jumping. Has 2nd pair of wings. Contains spiracles * SPIRACLES - An opening in the exoskeleton through wh/ air exchange can take place for respiration spiracles

- Consists of 10 segments on a grasshopper 3. Abdomen Region: - Consists of 10 segments on a grasshopper - Contains spiracles (1st 8 segments) - Contains TYMPANUM - Found on 1st segment of abdomen. Used for hearing

INTERIOR OF A GRASSHOPPER: *Respiration: Spiracles are openings to the exterior wh/lead into the trachea. It is here that oxygen will diffuse into the tissues and carbon dioxide out of the tissues *Digestive System: - Consists of: Mouth, Esophagus, Crop, Gizzard (grind food), Midgut, Hindgut, Intestine (Colon), Rectum and Anus - The GASTRIC CECA produces and secretes enzymes into the midgut for the digestion of food

*Excretory System: System for the removal of metabolic waste - The grasshopper uses MALPIGHIAN TUBES for the removal of metabolic waste + Located at the junction of the midgut and hindgut * The grasshopper has a ventral nervous system midgut hindgut

- Open circulatory system wh/ is dorsal - Poorly developed - The system consists of blood sinuses *Reproduction: - Separate sexes - Female produces eggs and deposits them by the OVOPOSITOR in late summer or fall - Eggs lie dormant in the soil during the winter - Nymphs will hatch in the spring