INSECTS AFFECTING PARK AND WOODLAND TREES 



485 



Owl beetle 



Alans oculatus Linn. 

 A large, rather stout, black, white-marked beetle, ^y 2 inches long, bearing two 

 conspicuous eyelike spots, is frequently met with in decaying wood. 



There are a number of insects brought to the attention of the ento- 

 mologists from year to year on account of some peculiarity and such is the 

 case with this species. Its conspicuous eyelike spots on the prothorax 

 excite the attention of even the most casual observer, and as the beetle is 

 not very common, most specimens observed are captured, and are very 

 likely to find their way into the hands of some entomologist. 



This species cannot be considered - injurious, since it occurs only in 

 decaying wood, and the observations of Dr Lugger would seem to indicate 

 that it can be classed among our beneficial species. He has found in his 

 own experience that it was impossible to rear the larvae or grubs, unless 

 they were provided with living insects which they soon found and devoured. 



Description. This large snapping beetle ma)' be easily recognized by 

 reference to plate 39, figure 2, which shows it about natural size and repre- 

 sents, the appearance of a well marked individual. The conspicuous eyelike 

 spots are found only in one other native beetle, a very rare species. This 

 insect is representative of a very large family, members of which possess 

 the power of projecting themselves upward suddenly by the means of a 

 peculiar springing apparatus on the ventral surface. A stout spine on the 

 thorax projects back in a socket in the abdomen and by bending its body 

 backwards, the beetle can raise its spine and rest it on the edge of the 

 socket, and then with a sudden muscular exertion, spring it back into the 

 cavity. The result is that the beetle is thrown into the air to a hight sev- 

 eral times its length. This device is apparently for no other purpose than 

 to enable the insect to regain its feet, evidently very useful, since this beetle 

 and its allies are nearly helpless whenever they fall on their back. This 

 peculiar snapping has led to these insects being called snapping or click 

 beetles, and the entire family, which is composed of a large number of 

 forms, are known to scientists as Elateridae. 



