LARVAL SACRIFICE 389 



of victims, the total bulk and food value of each cell's con- 

 tents remain the same. 



Two days after the egg is deposited and the cell sealed 

 up with clay, the young roach-killer hatches. It is but a tiny 

 grub of thirteen segments, two millimeters in lengi;!!, rather 

 transparent and concerned only witli its mouth and digestive 

 tract. For two days it gorges, selecting only the tenderest, 

 juiciest parts of its victims, leaving the legs and other less 

 nutritious parts untouched. On the fifth day of its exist- 

 ence, it returns to these left-overs, going over and over them 

 until all nourishment is gone. 



One hears the glutton plainly at its feast. Sip-sip-sip, 

 comes the rythmic sound. Its entire body throbs in unison 

 as the greedy creature dives deeper and deeper into the grab 

 bag of the roach's anatomy. In five days the feast is over. 

 The wings, egg cases, shells of the heads and thorax, together 

 with the hard limb skeletons of the roaches are left uneaten 

 in the end. They lie about the cell in fine disorder as lasting 

 evidence of the grub's revelry. 



Immediately upon finishing the repast, the larva con- 

 structs a network of silken threads, just enough to prevent 

 its rolling about. Within this cradle an inner cocoon is 

 formed, composed of threads much more densely spun, and 

 finally coated within with a reddish brown fluid that hardens 

 in contact with the air, into a brittle skin. The process of 

 spinning and coating requires eighteen hours for completion 

 after which the larva excretes the waste from its five-day 

 gorge in a single mass at one end of the cocoon. 



Spinning over, there comes a ten-day pause in the crea- 

 ture's activity, during which time w^e shall witness the Lar- 

 val Sacrifice. This process, known as pupation, is in many 

 respects the strangest and most wonderful of all physiolog- 

 ical transformations tliat take place in the insect world. We 

 will see- the grub wliich in reality is but the ancestral form 

 of the wasp,, transformed by what we might call a "second 

 birth," from its lowly worm-like })odv into an utterly differ- 



