36 INTERRELATIONS OF PLANTS AND ANIMALS 



are not alone sufficient identification, as they 

 may or may not be present. A jointed pro- 

 boscis which points 



backwards is the 

 only sure means of 

 knowing this group. 



Beetles (Coleoptera, sheath wings). — • 

 Characterized by having a strong front pair 

 of wings called elytra, usually covering the 

 hind wings and always meeting in a straight 

 line down the middle of the back. Mouth 

 parts hard, pincher-like jaws. 



a. Field Work 



Method. — Collect as many different kinds of insects as you 

 can, making careful notes as to the locality where the insect was 

 found, the flowers which it frequents, the kind of food it was tak- 

 ing from the flower, and the order to which it belongs. 



b. Laboratory Work 



Observations. — From boxes containing a number of different 

 insects pick out one from each order given above and give your 

 reasons for placing that particular insect in the order which you 

 have chosen for it. 



Conclusion. — 1. Why do certain insects always frequent 

 certain flowers ? Look at the insect, especially the mouth parts, 

 verjr carefully and study the form of the flower before making your 

 decision. 



2. How would you pick out (a) a bee, (b) a butterfly, (c) a bug, 

 (d) a grasshopper from the above insects? 



Problem 11 : To study the life history (.metamorphosis') of 

 an insect. 



NOTE. — Field work may be done at a museum, or questions may be worked out 

 from some of the excellent preparations made by the Kny-Scheerer Company or 

 other of the biological supply houses. 



