The Grasshopper: A Typical Insect (1955)

[Music] the grasshopper is one of the most common and widely known insects in the world destruction of many crops by grasshoppers has been known to man since ancient times understanding the grasshoppers habits has helped us control this pest one reason we study the grasshopper is that its body is a good example of the basic structure of all insects another reason is that its life cycle is typical of those insects that develop through the process of incomplete metamorphosis these characteristics are also found in the grasshoppers relatives the mantis the cricket and the katydid let's look first at the basic body structure of the grasshopper like all insects it has a head thorax abdomen and three pairs of legs on the head of the grasshopper we notice the antennae and the eyes all insects have antennae and use them in feeling and smelling the grasshopper like most insects has a pair of compound eyes these eyes are made up of many six sided parts known as facets here magnified many times their normal size compound eyes enable the grasshopper to see in almost all directions without turning its head close to the compound eyes are smaller eyes called oscelli these simple eyes help the insect distinguish between light and dark like many other insects grasshoppers feed on plants eating rapidly they tear away at the plants using their strong jaws at this rate we can see how quickly a swarm of grasshoppers can destroy a field the grasshopper uses its four legs to hold the plant it eats altogether it has three pairs of legs the six jointed legs common to all insects the hind pair are large muscular legs that are used for jumping some kinds of grasshoppers travel by using their wings wings are another body structure common to most grasshoppers and to many other insects another structural feature of insects is their breathing apparatus like all insects grasshoppers breathe through spiracles small openings along the thorax and abdomen at the end of the abdomen are the over positors or egg placers of the female grasshopper with the ovipositors the female bores a hole in the ground to lay her eggs a single female grasshopper may lay from 25 to 100 eggs usually in the autumn here are the eggs the first step in the grasshopper's life cycle a life cycle of incomplete metamorphosis next the eggs hatch in the spring watch the ground carefully to see the newly hatched grasshopper or nymph emerging the nymphs resemble adult grasshoppers they have huge appetites and eat so much that they soon outgrow themselves this has happened to the nymph on the right as the nymphs body outgrows its heart outer covering this covering the exoskeleton splits and a larger nymph emerges this process is called molting and occurs five times in the grasshopper's life cycle let's watch this molting process once more with the action speeded up out comes the nymph and left on the dandelion is the empty exoskeleton the hard outer covering insects that resemble the adult upon hatching and go through several moltings illustrate incomplete metamorphosis we have seen that the grasshopper is typical in structure of all insects having a head thorax abdomen and three pairs of legs we have seen that its life cycle is an example of incomplete metamorphosis we have seen that it can cause much damage to man's crops by studying the grasshopper we become more familiar with one of the most common examples of the world of insects [Music]