4io 



Handbook of Nature-Study 



Eggs of Colorado potato- 

 beetle. 



Photo by Slingerland. 



their skins. They do this four times, and during the last stages, are 



very conspicuous insects on the green leaves; 

 they are orange or yellow with black dots 

 along the sides, and so humpbacked are they 

 that they seem to be "gathered with a pucker- 

 ing string" along the lower side. It requires 

 from sixteen days to three weeks for a larva 

 to complete its growth. It then descends into 

 the earth and forms a little cell in which it 

 changes to a pupa. It remains in this con- 

 dition for one or two weeks, according to the 

 temperature, and then the full-fledged beetle 

 appears. The entire life cycle from egg to 

 adult beetle may be passed in about a 

 month, although if the weather is cold, this 

 period will be longer. The beetles are very 

 prolific, a mother beetle having been known 

 to produce five hundred eggs, and there are 

 two generations each year. These beetles 

 not only damage the potato crop by stopping 



the growth through destroying the leaves, but they also cause the 



potatoes to be of inferior quality. 

 The adult beetle is an excellent 



object lesson in the study of beetle 



form. Attention should be called 



to the three regions of the body: A 



head which is bright orange; the 



compound eyes, which are black; 



and three simple eyes on the top 



of the head, which are difficult to 



see without a lens. The antennae 



are short, their joints easily noted, 



and special attention should be paid 



to their use, for they are constantly 



moving to feel approaching objects. 



The two pairs of mouth palpi may 



be seen, and the beetle will eagerly 



eat raw potatoes, so that the pupils 



may see that it has biting mouth- 



parts. The thoracic shield is 



orange, ornamented with black. 



The three pairs of legs are short, 



which is a proof that these beetles 



do not migrate on foot. The claws 



and the pads beneath can be seen 



with the naked eye. Each wing- 



Larvae of Colorado potato-beetle. 

 Photo by Slingerland. 



cover bears five yellow stripes, also five black ones, although the outside 

 black stripe is rather narrow. These beetles are very successful flyers. 

 During flight, the wing-covers are raised and held motionless while the 

 gauzy wings beneath are unfolded and do the work. Children are 

 always interested in seeing the way the beetles fold their wings 

 beneath the wing-covers. 



