84 OUR INSECT FRIENDS AND FOES 



the juices of their prey. The slender body of 

 the Whirligig larva is nearly three-quarters of 

 an inch in length, and the three pairs of legs 

 attached to the under thoracic segments are 

 moderately long and slender. Each of the first 

 eight abdominal segments bears a pair of 

 delicate, feathery gills, the ninth segment 

 being provided with two pairs. The small 

 tenth segment carries two pairs of long and 

 sharp, curved hooks, which are used in climbing 

 amongst the water-weeds, etc. Very few 

 naturalists seem to have been able to observe, 

 in its natural environment, the larva forming 

 its cocoon in which to pupate. According to 

 Modeer, the full-grown larva quits the water 

 about the first week in August, by climbing 

 up the stem of a water-plant, and then spins 

 a greyish cocoon, which is pointed at both 

 ends. Pupation then takes place, the perfect 

 beetle emerging about the end of August or 

 the beginning of September. 



The large compound eyes of the Whirligig 

 Beetle are divided into two separate portions, 

 so that one-half of the facets are on the under 

 surface, as it were, and the other half directly 

 above. This curious division of the eye has 

 been thought to be a special modification, 

 enabling the beetle to keep a simultaneous 

 watch aloft and below, but this theory needs 

 verification by more careful observation. The 

 three pairs of legs are interesting, on account 

 of their special modification of form to meet 

 the needs of the Beetle. The front pair are 

 the longest, are slender, and in the male bear 



