INSTINCTIVE BEHAVIOUR IN INSECTS 73 
species or genera, while Philanthus punctatus preys chiefly or 
entirely on bees of the genus Hualictus. 
Romanes * thought that the manner of stinging and para- 
lyzing their prey might “be justly deemed the most remarkable 
instinct in the world.” Spiders, insects, and caterpillars are 
stung, he says, ‘in their chief nerve-centres, in consequence 
of which the victims are not killed outright, but rendered 
motionless ; they are then conveyed to a burrow and, continu- 
ing to live in their paralyzed condition for several weeks, are 
then available as food for the larvee when these are hatched. 
Of course the extraordinary fact which stands to be explained 
is that of the precise anatomical, not to say also physiological 
knowledge which appears to be displayed by the insect in 
stinging only the nerve-centres of its prey.” Eimer + thought 
that it “is absolutely impossible that the animal has arrived 
at its habit otherwise than by reflection upon the facts of 
experience.” “At the beginning,” he says, “she probably 
killed larvee by stinging them anywhere, and then placed them 
in the cell. The bad results of this showed themselves ; the 
larvee putrified before they could serve as food for the larval 
wasps. In the mean time the mother wasp discovered that 
those larvee which she had stung in particular parts of the 
body were motionless but still alive, and then she concluded 
that larve stung in this particular way could be kept for a 
longer time unchanged as living motionless food.” 
Now, since these wasps, when they have stored their nests 
and laid an egg on one of the victims, close it up once and for 
all, and take no further interest in it or its contents, there 
seems no opportunity, at any rate in the existing state of 
matters, for the acquisition of that experience on which Eimer 
relied. But both his explanation and Romanes’s difficulty are 
based on the following assumptions: first, that the victims 
are instinctively or habitually stung in the chief nerve-centres ; 
secondly, that when thus stung they are not killed but remain 
paralyzed for weeks ; and thirdly, that the marvellously definite 
* “Mental Evolution in Animals,” p. 299. 
+ “Organic Evolution,” translated by J. T. Cunningham, p. 280. 
