294 HYMENOPTERA 



I tried to dig up the contents of the burrow, but failed, 

 and am at a loss to know what is the explanation of the 

 intrusion. Unfortunately the Lycoid fossor was not 

 caught for identification. 



Another family of Fossores is the Sphegidae, which 

 contains insects of very varied size and habits, although 

 they all agree in storing up paralysed insects or spiders 

 for their young. The species of prey chosen by Sphegids 

 differ greatly ; some choose spiders, many more grass- 

 hoppers or crickets, and many others the smooth bodied 

 caterpillars of Noctuid or Geometrid moths, but never 

 hairy caterpillars such as those of Arctiidae or Lymantridae, 

 though I have seen one species taking a pilose Lycaenid 

 caterpillar into its burrow. If the species selected is of 

 small size, a number must be collected, but very often 

 a single individual furnishes all the food that a Sphegid 

 larva requires. 



Although they all belong to the natural group Fossores, 

 the Sphegidae do not all dig in the ground. 



A dead bough that contained a nest of a large Carpenter 

 bee was also used by a large black Sphegid for its brood. 

 A tunnel about half an inch in diameter had been exca- 

 vated, and the mouth was stopped up by little pieces 

 of wood and lichen. It penetrated perpendicularly into 

 the wood for about an inch and then turned sharply to 

 the right and ran longitudinally about four inches. At 

 the end was a collection of the remains of some half- 

 dozen small Locustidae, and a cocoon about an inch and 

 a half long, formed of an outer silky and an inner papery 

 layer. Inside the cocoon was the larva, and six small 

 larvae, probably Diptera, which were presumably indirect 

 parasites like Idia. Beyond the cocoon the passage was 

 directed towards the centre of the bough, then turned 

 to the left for two inches, and eventually opened to the 

 exterior below the original opening. This second orifice 

 was not stoppered. It is much to be regretted that 



