in SPHEGIDAE SPHEGIDES 109 



wards. The habit of depositing its prey on the ground enabled 

 Fabre to observe the process of stinging; this he did by himself 

 capturing a cricket, and when the wasp had momentarily quitted 

 its prey, substituting the sound cricket for the paralysed one. 

 The Sphcx, on finding this new and lively victim, proceeds at 

 once to sting it, and pounces on the cricket, which, after a brief 

 struggle, is overcome by the wasp ; this holds it supine, and then 

 administers three stings, one in the neck, one in the joint between 

 the pro- and meso-thorax, and a third at the base of the abdomen, 

 these three spots corresponding with the situation of the three 

 chief nervous centres governing the movements of the body. 

 The cricket is thus completely paralysed, without, however, being 

 killed. Fabre proved that an Insect so treated would survive for 

 several weeks, though deprived of all pow r er of movement. 

 Three or four crickets are placed by the wasp in each cell, 100 

 individuals or upwards being thus destroyed by a single wasp. 

 Although the sting has such an immediate and powerful effect 

 on the cricket, it occasions but a slight and evanescent pain to a 

 human being ; the sting is not barbed, as it is in many bees and 

 true wasps, and appears to be rarely used by the Insect for any 

 other purpose than that of paralysing its victims. The egg is 

 laid by the Sphex on the ventral surface of the victim between 

 the second and third pairs of legs. In three or four days the 

 young larva makes its appearance in the form of a feeble little 

 worm, as transparent as crystal ; this larva does not change its 

 place, but there, where it was hatched, pierces the skin of the 

 cricket with its tiny head, and thus begins the process of feed- 

 ing ; it does not leave the spot where it first commenced to feed, 

 but gradually enters by the orifice it has made, into the interior 

 of the cricket. This is completely emptied in the course of 

 six or seven days, nothing but its integument remaining ; the 

 wasp-larva has by this time attained a length of about 1 2 milli- 

 metres, and makes its exit through the orifice it entered by, chang- 

 ing its skin as it does so. Another cricket is then attacked and 

 rapidly consumed, the whole stock being devoured in ten or t \\el\e 

 days from the commencement of the feeding operations ; the con- 

 sumption of the later-eaten crickets is not performed in so delir.-ne 

 a manner as is the eating of the first victim. When full-grown, 

 the process of forming a cocoon commences: this is a very ela- 

 borate operation, for the encasement consists of three layers, in 



