58 GENERAL SCIENCE 



The honeybee and the silk worm contribute to his well-being. 

 But in spite of their marvelous beauty of form and coloring, 

 and all the wonder which their structure and transformations 

 and adaptability to changing conditions may call forth, 

 insects are generally to be regarded as pests. They are a 

 destructive agency against which ceaseless warfare is to be 

 waged. There are more known species (various kinds) of 

 insects than there are species of all other animals combined. 

 So great is the number of insects that they are said to com- 

 prise three-fourths of the animal kingdom. Any good text 

 on animal biology will furnish information of greatest worth 

 concerning insects. We do not need to be scientists, 

 however, to acquire sufficient knowledge of this group of 

 animal life to understand how our health and comfort are 

 affected by them. 



In a general way the bodies of insects may be described as 

 consisting of head, thorax, and abdomen. On the head are a 

 pair of relatively large eyes, and two antennae or "feelers." 

 Attached to the thorax are two pairs of wings above, and 

 three pairs of jointed legs below. The abdomen is made up 

 of a series of rings or segments. Moths, bees, flies, butter- 

 flies, or grasshoppers may be chosen for making studies of 

 insects. A pocket lens is a great aid in making these studies. 



The feet and body of the common house fly as seen under 

 a magnifying glass appear hairy. A sticky secretion on the 

 feet of the fly enables it to walk on smooth surfaces, and in 

 all manner of positions. As the common house fly revels in 

 filth of all kinds it is a menace to health everywhere it goes. 

 There is always the possibility of germs of typhoid, tuber- 

 culosis, or dysentery being left by flies on foodstuffs, and on 

 the dishes used in kitchen and dining room. The female 

 fly may lay one hundred eggs or more at a time, and under 

 favorable conditions these may hatch within a day. The 

 larva (grubs, or maggots) grow rapidly, especially if lodged 



