SOME SUGGESTIONS FOE THE STUDY OF INSECTS. 155 



last.* 'The last segment differs slightly in shape from the 

 others. All these points will be seen clearly as the pupils 

 make their drawing. 



On the sides of the caterpillar's body may be seen minute 

 oval areas, whitish in colour. In some species they appear 

 quite conspicuous, although they are never very large. In 

 the caterpillar we can see a pair of these on each segment 

 behind the head except the last two of the thorax. These 

 should be looked for. They are of interest, since they have 

 slit-like openings through which the caterpillars breathe, 

 air passing in and out with the movements of the body. 

 The caterpillar should be drawn with body extended 

 (Fig. 55'). 



Having become familiar with the leading external 

 features, we may proceed to watch the caterpillar moving. 

 Our next drawing must show how it progresses. Releasing 

 its hold by its sucker feet it draws its body into a loop, 

 placing segment ten close behind segment four (Fig. 55 2 ). 

 Next, releasing the hold of the thoracic feet, the body is 

 raised (Fig. 55 3 ), stretched forward, and laid down fully 

 extended, a hold being taken again by the thoracic feet. 

 Once secure, the hind part is released, the body arched as 

 before, and so the process is repeated, the creature pro- 

 gressing by a series of looping movements. Caterpillars 

 belonging to this family are popularly known as " loopers " 

 on account of this habit. Pupils may be able also to see 

 the appropriateness of the scientific name of the Family 

 Geometridae or " earth measurers." 



A common experience, which doubtless will be shared 

 by pupils when collecting, is to find that the caterpillar 

 disappears as the hand is put out to remove it. They are 

 usually more or less concealed amongst the foliage ; fre- 

 quently they rest against the leaf stalk. In the act of 

 reaching towards the caterpillar we inevitably shake the 

 bush and the caterpillar falls. Usually* the actual fall is 



* Caterpillars mostly have more sucker or stump feet. The 

 maximum number is ten stump feet for a true caterpillar (see 

 Fig. 164, p. 306). 



