PROCESSIONARY MOTH. 575 



but in the middle of the nest is one grab of very great size, 

 being, in fact, six or seven time as large as the caterpillars. This 

 creature has been introduced because it is generally to be found 

 in the nest of the Processionary moth, and because it is one of 

 the most useful insects that a careful agriculturist can protect. 



It is the larva of a beautiful beetle, called scientifically 

 Calosoma sycophanta, which is represented below in the act of 

 ascending the tree. The beetle is a lovely blue-green, but the 

 larva is as unsightly a being as can well be conceived, its body 

 being fat, flattish, and scaly, and its colour black. This creature 

 feeds entirely upon the various caterpillars and other larvae, even 

 eating those of the destructive sawflies. At the end of the tail 

 are two horny spines, and the head is furnished with a pair of 

 curved, sharp, and powerful jaws, by means of which it seizes 

 its prey. 



Instinct teaches these grubs to find their prey, and it may 

 easily be imagined that when they approach a nest of the Pro- 

 cessionary moth they are not slow to avail themselves of the 

 opportunity. Indeed, so sure are they of discovering their prey, 

 that E^aumur asserts that he never opened a nest of the Proces- 

 sionary moth without finding one or more specimens of their 

 rapacious enemy, as many as five or six having been seen in a 

 single nest. They are most voracious creatures, as indeed is 

 evident from their structure ; and, as each grub will eat several 

 large caterpillars in a day, the havoc which is made in the nest 

 may easily be imagined. The caterpillars have no means of 

 defence or escape. They cannot leave their home, and they 

 cannot kill or expel the intruder. All that they can do is to 

 go out and eat, and come back and be eaten, their numbers ever 

 diminishing, like the companions of Ulysses in the Cyclops' 

 cave. 



But for the exertions of this most useful insect, the ravages of 

 the Processionary caterpillars would be greatly increased, for the 

 creature does not only eat them while in the larval condition, 

 but feeds upon them after they have become pupae. Sometimes, 

 however, this extreme voracity defeats its own purpose. It 

 occasionally happens that a grub of the Calosoma habitually 

 gorges itself to such an extent with Processionary caterpillars 

 that it becomes fat, imwieldy, and scarce able to move. If, when 

 it is in this condition, leaner and hungrier grubs should come 



