Name: ___________________________ Date: __________________

Each sentence needs one or more semicolons or commas. Insert the appropriate marks for each sentence below.

1. Each year many species of birds fly south for the winter; for example, ducks and geese migrate to warmer areas to find more abundant food.
   
   
2. Most insects cannot fly the distances that these birds can fly; instead, they time their development so that they are in eggs or cocoons during the winter.
   
   
3. There is one exception, however; the Monarch butterfly is different from other insects.
   
   
4. Birds avoid lethal cold by getting away from it; the Monarch butterfly does the same thing.
   
   
5. The long, hot days begin to grow shorter; the temperatures grow colder; and the beautiful black and orange Monarch butterflies know that it's time to make their amazing journey.
   
   
6. These butterflies have tiny insect brains; however, those brains somehow guide the butterflies over thousands of miles they've never seen before.
   
   
7. On their way to central Mexico, eastern Monarch butterflies stop in places such as San Angelo, Texas; Bracketville, Texas; and Eagle Pass, Texas.
   
   
8. Thousands of them travel together in the same "flyaways"; to see all of them flying together is truly awesome.
   
   
9. They don't mind crowds; as a matter of fact, a ten-acre colony can contain five to six million butterflies per acre.
   
   
10. Biologists estimate that 15,000 to 20,000 butterflies perch on a single tree bough; as a result, the trees appear to be covered with bright autumn leaves.
    
    
11. They arrive in their winter home in November, and they remain until March of the next year.
    
    
12. The Monarch butterfly breeds four or five times per year in a cycle; each generation migrates either north or south.
    
    
13. The generation of butterflies that migrates to Mexico returns to the Gulf Coast states of the South, and this generation lays eggs on milkweed plants.
    
    
14. The next generation lives only four to six weeks; its mission is to get to the northern states and southern Canada.
    
    
15. Milkweed is plentiful at north latitudes, so the butterflies spend their summer there eating and increasing their numbers.
    
    
16. Milkweed is the only thing these butterflies eat, and this plant has one additional benefit.
    
    
17. Milkweed contains toxins; therefore, the butterflies become poisonous to predators when they ingest these toxins.
    
    
18. These butterflies need no camouflage, for their bright colors signal poison to animals looking for a snack.
    
    
19. The generation that makes the journey to Mexico is rewarded for its hard work with a longer life; those butterflies live eight months instead of two.
    
    
20. The Monarch butterfly is a fascinating creature, and its travels are one of the world's biological wonders.