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in the tropics, be he agriculturist or otherwise, has thus his attention 

 continually directed towards the six-legged winged creatures, either in 

 admiration of their form and beauty, or, perhaps more often, in execra- 

 tion at the petty annoyances to which they subject him and the more 

 serious damage to agriculture resulting from their activities. 



Seeing that insects have such a constant influence and importance in 

 our daily lives we shall observe them with greater interest, may appre- 

 ciate more their presence, or be better able to deal with them as pests, 

 when we know somewhat of their organization and habits. Fortu- 

 nately there is a general plan of structure applicable to insects, which 

 is readily grasped, and which enables us easily to distinguish them from 

 all other animals. Other characters again ally them to creatures appear- 

 ing at first sight very distantly removed. Primarily we observe their bo- 

 dies to be made up of distinct rings or segments. This ringed body 

 they have in common with worms, centipedes, lobsters, scorpions, and 

 spiders. Their paired legs are likewise seen to be constructed of several 

 parts separated by joints, differing in form and purpose according to the 

 position in the body of the part we select. In this they differ entirely from 

 tha segmented worms, which have only hairs or bristles to aid them in 

 locomotion, but agree with the remaining groups mentioned This com- 

 mon character of the appendages enables us to form a great group of 

 the animal kingdom, the Arthropoda, or jointed-footed animals. By 

 the number of these feet we can also separate the insects from most of the 

 other members of the Arthropoda. The centipedes, lobsters, etc., have 

 a pair, of one shape or another, to every ring ; scorpions and spiders 

 have four pairs restricted to the front segments, but insects are all 

 limited to three pairs of true walking legs in the middle division 

 of their body. Again, lobsters and spiders have the whole body 

 divisible into two main portions ; insects have, with few excep- 

 tions, three distinct and separate regions — -the head, thorax, and 

 abdomen. Finally, insects differ most advantageously from all other 

 arthropods in the possession of wings ; usually two pairs fixed to the 

 two last rings of the thorax. These are to be regarded as outgrowths 

 from the body ; perhaps, with their hollow veins, developed primarily 

 for respiratory purposes, but afterwards taking on the very important 

 function of aerial locomotion. 



By their means insects alone, among the invertebrates, occupy an 

 exalted and active position in the air, such as is occupied by the birds 

 among the vertebrates. To the gift of wings must be attributed 

 the wonderful numerical success of insects in the struggle for existence, 

 as well as that of birds ; and, in a measure, their advance in uctivity and 

 intelligence. To sum up, insects are distinguished from all other ani- 

 mals by the following combination of characters : The division of the 

 body into three regions, head, thorax, and abdomen, the two first being 

 separated by a well defined neck ; the possession of one pair of feelers 

 or antennas on the head ; the thorax with only three segments, each 

 bearing a pair of jointed legs, and usually a pair of wings to the two last 

 rings ; and, lastly, the abdomen with nine or ten segments. 



The paired eyes on the head are generally fixed and differ much 

 in plan from the eyes of higher animals, each being a combination 

 somewhat equivalent to very numerous single eyes. Experiments seem 

 o point to the conclusion that insects cannot distinguish by their eyes 



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