24 THE WHITP:-GRUBS. 



disturbed, however, no amount of rain or severe cold will 

 injure them. The old belief that insects go into the ground 

 simply to protect themselves against cold is difficult to be- 

 lieve, for if they had to go below the frost-line in Minnesota 

 they would have to go eight feet deep, and would have to 

 be equiped with wonderful organs for such a purpose. 



A second and much larger species is very destructive in 

 our state; it occurs both in the wooded and in the prairie 

 region. It is LacJiiiosterna riujom- Melsh., a reddish-brown 

 smooth beetle with a very rugose thorax. It is shown in 

 fig. 15, plate II). This is the white grub that causes the 

 most damage in our state and whose larva is so frequently 

 mentioned in agricultural and horticultural papers. During 

 the past season this insect has been especially destructive to 

 lawns, and has caused a great deal of anno^'ance to those 

 in charge of our public parks and cemeteries. In one case 

 many acres of the most perfect lawns were destroyed in a 

 cemetery, where large patches of grass turned yellow; when 

 such spots were investigated it was found that the whole 

 sod could be lifted from the ground, the grubs having cut 

 off all the roots. The illustration showing the white-grubs 

 (fig. 16, plate III) was taken from such larv^ found in the 

 act of cutting off the roots. The3% as well as those of related 

 species, do not move in the usual way by means of their 

 legs, but push themselves forward in a peculiar wa3^ by 

 a wriggling motion of their backs. In other words the lar- 

 vae use their backs for locomotion, and their legs are simply 

 utilized to pull the roots of plants toward their very hard 

 and horny jaws. When we look at the peculiar shape of 

 white-grubs we can clearh' perceive why the legs are not 

 used for locomotion, nor is much locomotion required, as 

 they live underground in very short tunnels where they need 

 to move but little, being surrounded by plent^^ of food. 

 Some of our cultivated plants suffer very severely from the 

 attacks of these insects and this is especially true of such 

 plants as strawberries, and whole fields of them are de- 

 stroyed from time to time. As these larvae live under the 

 ground they are not readily reached hy insecticides, and 

 consequently they can not be be poisoned like potato beetles 



