Beneficial Insects 



for some unfortunate insect to pass near. When one comes within reach 

 the jaws snap shut and the victim is drawn into the burrow and devoured. 



In order to prevent some stronger insect from dragging the young 

 tiger-beetle from its burrow, nature has provided it with a peculiar anchor 

 in the form of a hump on the fifth segment of its abdomen. This hump 

 is armed with several curved hooks which fasten into the walls of the 

 burrow, thus making it possible for the larva to withstand the pull of a 

 powerful victim. 



The adults (Figs. 6 and 7, Plate IX, Page 27) are usually a metallic 

 green or bronze banded with light markings, from which comes the name 

 "tiger-beetle." However, some are black, while others are light, in har- 

 mony with the color of the sand on which they live. 



3. LADY-BEETLES OR LADY-BUGS 



(Figs. 14, 15, 23 and 24, Plate IX, Page 27; Figs. 10 and 15, Plate II, Page 13; 

 Fig. 14, Plate VII, Page 23) 



The lady-beetles, or lady-bugs, as they are commonly called, are 

 among the best known and most important predacious insects. 



Both the adults and larvae feed upon small, soft bodied insects and 

 insect eggs. 



These beetles have the peculiar habit of congregating in very large 

 numbers in the fall of the year just before going into hibernation. At 

 such times they can be scooped up by the quart as they cluster about the 

 bases of trees and shrubs or under stones, in layers many deep. Such a 

 congregation of the species discussed below occurred at the very top of 

 one of the highest mountain peaks near the city of Denver in 1916. 



Hippodamia convergens (Fig. 15, Plate IX, Page 27) is the com- 

 monest of all species. This, together with several others, is especially 

 noted for the numbers of plant-lice which it destroys. The larva (Fig. 23, 

 Plate IX, Page 27) is a common object among colonies of plant-lice, 

 where the pupa (Fig. 24, Plate IX, Page 27) is also often encountered 

 fastened to a twig or leaf. Other species are especially useful for their 

 work in orchards, where they devour scale insects which would otherwise 

 injure the trees and fruit. Figure 10, Plate II, Page 13 shows a lady- 

 beetle which feeds upon sugar beet root-lice. Figure 15, Plate II, Page 

 13 shows the larva, and Figure 14, Plate VII, Page 23, the pupa, of this 

 same beetle. 



The eggs of lady-beetles vary with the species, as does the place 

 selected for depositing them. Those of our common forms resemble 

 the eggs of the Colorado potato-beetle, but are smaller. They are de- 

 posited in clusters, the eggs standing on end. A cluster of the eggs of 

 Hippodamia convergens is shown in Figure 14, Plate IX, Page 27. 



4. TRUE BUGS 



(Fig. 14, Plate II, Page 13) 

 The majority of the true bugs are vegetable feeders, and pests of the 

 first magnitude. However, several families contain species which are 

 predacious, feeding upon the blood of other insects or the higher animals, 

 which is sucked up through their strong, jointed beaks. 



132 



