THE SOCIAL WASPS. 345 



After the appearance of four workers, fresh caterpillars were repeatedly 

 offered them. Two weeks passed before this met with any response, 

 whereupon one day they all surprised me by coining up and very eagerly 

 preparing and distributing the food. I have since made sure that the 

 nursing habit is entirely independent of the example of the mother and, 

 further, that its appearance is to some extent variable for different 

 individuals. 



In the experiments conducted the past summer, bits of the larvae of 

 the Eibbed Ehagium, a beetle whose eggs develop under the bark of 

 decaying trees, were offered at intervals to the newly excluded neuters 

 before they had had any association with others of their kind. With 

 slight exception, great trepidation, or rather movements which I 

 interpret as indicating fear, was shown at the first appearance of the 

 morsel. The wasp retreated precipitately from the proffered morsel, 

 sometimes turning and running away in the wildest manner imaginable. 

 But usually when the bit had been presented for the fourth or fifth time 

 (at intervals of one half to one minute), the wasp would no longer 

 back or run away, but stop and look at it. The next action was to touch 

 it with the antennas and finally it was seized and disposed of in the cus- 

 tomary manner. Usually the experiment met with success in the way 

 described if performed any time after the first half day of imaginal 

 life. But I have seen a worker not four hours old spontaneously go 

 through the same reaction while others waited several days before mani- 

 festing the instinct. 



The whole process seems to be a reflex called forth by the presence 

 of the food, and an important factor in calling it forth is hunger on the 

 part of the wasp. It is highly probable that in the crushing process 

 liquids are extracted from the mass, which are swallowed by the wasp. 

 I have frequently seen them chew at morsels without molding or mixing 

 them, and even dropping the mass to lap up the liquid which had 

 exuded from it. Once started, however, the reflex unfolds in the natural 

 order, first the crushing and molding, then a slow marching round the 

 nest with frequent pauses, and, if larva? are present, the pinching off of 

 the food bit by bit until all has been disposed of. If no larvae are 

 present, if, for instance, the young worker is living in an inverted 

 tumbler and has never seen a larva the various stages in the process are 

 the same. It will run searchingly over the glass and pause every few 

 seconds to thrust the ball against it. This naturally meets with no suc- 

 cess and the food is again worked over and the process repeated, per- 

 haps several times, before the bit is dropped and not again noticed. 

 Very rarely the wasp will attempt to fly with its burden, although 

 naturally, since it has had no association with a nest or larvae, it flies 

 nowhere in particular. These observations remind one strongly of 

 Faber's experience with the mason-bees which, when their half-built 



