THE COMMON AND MALARIAL MOSQUITOES 61 



ences. Note the number of times that the nymphs molt. 

 Note the process of molting. How long does it take the 

 nymphs to be come adults ? 



Note that the young squash bugs resemble the adults. 

 What do the* adults have that the nymphs lack? From 

 this study of life history, it will be seen that the squash 

 bugs do not pass through any remarkable or distinct changes, 

 for the young resemble the adults. Such insects are said 

 to have an incomplete metamorphosis. How does this com- 

 pare with the butterfly? 



The harlequin cabbage bug has an incomplete meta- 

 morphosis also. 



To what order do these insects belong ? Find out what 

 other insects belong to the same order. All of them have 

 an incomplete metamorphosis. 



The harlequin cabbage bug lays its barrel-shaped eggs 

 on the leaves of mustard, turnips, cabbage, etc. The life 

 history of this insect may be very easily followed in the 

 garden or in the laboratory. The eggs are conspicuous 

 and easily found. 



C. TOPICS FOR FURTHER STUDY. Write out a summary 

 of the life history of the insect studied, giving all the 

 changes. Write a list of the food plants of the insect. 

 Fix firmly in mind the mouth parts and the manner in 

 which these insects obtain their food. Compare with the 

 grasshopper. Bear in mind the kind of metamorphosis pos- 

 sessed by these bugs and the order to which they belong. 



XIX. THE COMMON AND MALARIAL MOSQUITOES 



Materials. Eggs and adults of common mosquito (Culex) and 

 malarial mosquito (Anopheles), glass jars, pond scum, watch glasses, 

 magnifiers, glass slides, cover glasses, compound microscope. 



