ISOPTERA 131 



" The fierce face of the young dragon is all concealed " by its 

 extensible lower lip, which folds up. With their strong jaws and 

 legs dragon-flies secure and devour their prey. They devour vast 

 numbers of larval mosquitos and are thus of great use to man. 

 Finally, the full-grown nymph creeps up some stem, and the 

 winged form of the imago or adult dragon-fly breaks through the 

 old skin and flies away into the air and sunshine to enjoy its 

 aerial life until the falling temperature ends its existence. 

 These beautiful creatures may be called creatures of the air, for 

 they actually feed upon the wing and may sometimes be seen 

 poised in mid-air as if resting. The adult devours many gnats 

 and mosquitos. There are two types of dragon-flies, one 

 which keeps its wings horizontal and one which folds its wings 

 together vertically over the back. 1 



The breathing of the nymphs is peculiar. " The caudal end 

 of the alimentary canal is lined with tracheae, and water is 

 alternately drawn into and expelled from this cavity. ' The 

 water may be expelled with such force as to propel the body 

 forward. So this has a locomotive function also." 



ORDER v. ISOP'TERA 



The Termites (Fig. 101), or so-called "white ants," are abun- 

 dant in the tropics, but less so in the United States. Where 

 they are numerous they become pests, destroying houses, furni- 

 ture, or anything made of wood. They are not ants, as may be 

 seen by their structure. 



The body is always soft and usually whitish in color, though 

 sometimes brown. "It is plump and slightly broader than 

 thick." In the union of the abdomen with the thorax the little 

 pedicel or stem found in the ant is lacking, the abdomen being 

 broad at the base. They are blind or have simple eyes. They 

 conceal themselves from the light. The slender antennae look 

 like strings of tiny beads. 



The young are all apparently alike when hatched, but by 



some means not understood they are afterward developed into 



soldiers, workers, males (kings), and females (queens). The 



winged males and females swarm, and each pair which is fortu- 



1 Damsel flies, Kellogg. 



