Herbivores: Of Locusts and Caterpillars


 

BACKGROUND

The farmers in the small community are celebrating the abundant crop of wheat growing in their fields. As far as the eye can see, golden heads of grain sway gently in the breezes. It won't be long until the much-anticipated harvest arrives. But the calm is broken by a huge, undulating cloud on the horizon. The cloud grows larger as it approaches. Instead of rain, the flying forms of locusts descend on the earth all around. The silence is broken by the continuous crackling sound of "munching". The farming community is experiencing a much-dreaded plague of locusts. Soon there will be little left of their crops. Locusts are insects -- more specifically a type of grasshopper. Periodically, the numbers of locusts can increase so dramatically that, when flying together, they can block the light from the sun. Locusts are herbivores, animals which feed on plants. Under normal conditions, there is a balance between plants, herbivores, and the animals which eat them (carnivores). But, when populations become very large, imbalance and destruction can result. This is what happens in a locust plague. 

INVESTIGATION  

PLACE TO BEGIN:   How much can a tiny insect eat?  How does the amount eaten compare to the weight of the insect?  

MATERIALS:
An insect cage (a jar will do -- with small holes punched in the lid); a caterpillar (grasshoppers do not survive well in captivity and are hard to catch!); leaves of the plant upon which the caterpillar was feeding; a balance or postage scale

DIRECTIONS:
Weigh some fresh leaves before placing them in the insect cage with the caterpillar and again after they have been feasted upon for a short period of time. The leaves should not have a chance to dry out (and thus reduce the weight). The difference in weight is approximately equal to the amount eaten. Add fresh leaves and add up all your measurements to get a total amount eaten over a period of time. The insect can be weighed before and after it has eaten.

GOING FURTHER: 
What kinds of plant leaves will a particular kind of caterpillar eat if given a choice?
How long would it take for an insect to eat an entire plant? [Estimate from time taken to eat one leaf and the number of leaves on a plant, with all leaves being of similar size.]

DEVOTIONAL  

Read the entire book of Joel, a short book, but one with many applications about judgment, discipline, end times, the Holy Spirit, and ultimate blessing for God's people. Note especially Joel 1:1-4; 2:13.

Calamities of all kinds are experienced by people now and in ages past. The answer to "why?" is sometimes evident at the time when it is the result of sin. To those, our only response should be a hard look at our lives and a turning away from any sin (repentance). For others we may not know the answer at the present time. But God can use even the calamities of life for our spiritual growth and for ultimate good. Plagues of locusts are mentioned several times in the Bible, and Joel refers to a particularly serious event.

APPLICATION QUESTIONS:
1. What evidence of sin and evil do you see in the world?  
2. In what area of your life do you see the need to turn away from sin?  
3. How does looking at the world through God's eyes make you see things differently?


CREATIVE ACTIVITY

Make a chenile insect. Take some chenile wire to fashion an insect, such as a grasshopper. Think about how its different parts are adapted to different life functions, such as jumping and eating. What happens when normal life activities get out of balance or out of control?



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