344 ANNUAL EEPOET SMITHSONIAN INSTITUTION^ 1915. 



pact, we shall find that they are made up of a number of parallel 

 cells connected by the inner surface, which, after being filled by the 

 wasp with spiders for the nourishment of the larvae, are closed so 

 carefully with bits of earth that they become invisible. 



To capture the spider the wasp often has to undertake a desperate 

 struggle armed with its formidable sting; if the insect succeeds in 

 stinging its prey, the conquest is easy, but the spider is not defense- 

 less. With astonishing rapidity the spider spins a sticky thread and 

 the struggle between the two adversaries begins. With great care 

 the wasp approaches the spider's web, and by a skillful maneuver 

 often succeeds in stinging its enemy. But the threads are sticky; 

 an imj^rudence, and the wings are caught. Immediately the spider 

 renders the wasp helpless in a network of threads and devours it. 

 When the wasp succeeds in touching the spider its sting does not 

 cause immediate death, but produces a state of paralysis. If the 

 spider were killed outright it could not be kept as reserve nourish- 

 ment, while) merely paralyzed, it lives and keeps fresh, though it 

 can not harm the larvae which are at this stage entirely defenseless. 

 Usually about 15 spiders are found in each cell. The lower part 

 of the cell is occupied by the larva of the wasp, which, after having 

 consumed the last spider, is transformed into a chrysalis in the inte- 

 rior of a capsule of reddish-brown parchment. 



III. 



While some insects build their nests above the ground, others try to 

 find security imderground for their offspring. Among these we may 

 mention the sacred Ateuchnis, belonging to the group of Coprophagids. 

 The Coprophagids are represented by many species, of which several 

 are characterized by brilliantly colored and metallic-looking elytra. 

 Their ball of provisions, of known origin, serves either for their own 

 nourishment or for that of their larvae. In the first case the ball is 

 pushed into a hiding place, where it is gradualh'^ consumed ; in the 

 other case the Coprophagid introduces an egg into the ball and 

 buries it. 



On the plains of eastern Africa, at the end of September and dur- 

 ing the month of October, these insects, especially the great black 

 scarab, Scarabaeus pustulatus^ may be seen making and rolling these 

 balls (pi. 3, fig. 2). Their ability to discover the necessary material is 

 remarkable. If not a single one of these insects has been noticed all 

 day, great numbers of them will be found running around antelopes 

 which have been recently shot down by hunters. 



It is extremely interesting to watch a scarab make one of these 

 food balls, during which process it is often necessary for the insect 

 to fight with its own kind. With the anterior edge of its head, which 



