240 INSECT LIFE 



XVII 



half-murdered gadfly, still struggling between the 

 feet of its assassin, I have seen the Bembex chew 

 the head and thorax of her victim. This habit, 

 peculiar to the Bembecids, shows that the Bembex 

 desires death, not paralysis, since she ends the life 

 of the Diptera with so little ceremony. Everything 

 considered, I think that on the one side the nature 

 of the prey, so quickly dried up, and on the other, 

 the difficulties of so vehement an attack, are the 

 reasons why the Bembecids serve up dead prey to 

 their larvae, and consequently provide it daily. 



Let us follow the Hymenopteron when it returns 

 with its captive closely clasped to the burrow. Here 

 is one — B. tarsata — coming loaded with a Bombylius. 

 The nest is placed at the sandy foot of a vertical 

 slope, and the approach of the Bembex is announced 

 by a sharp humming, somewhat plaintive, and only 

 ceasing when the insect has alighted. One sees her 

 hover above the bank, then descend, following the 

 vertical line slowly and cautiously, still emitting the 

 sharp hum. If her keen gaze should discover any- 

 thing unusual, she delays her descent, hovers a 

 moment, ascends again, redescends, then flies away, 

 swift as an arrow. In a few moments she returns. 

 Hovering at a certain height she appears to inspect 

 the locality, as if from the top of an observatory. 

 The vertical descent is resumed with most circum- 

 spect deliberation ; finally, she alights without hesita- 

 tion at a spot which to my eye has nothing to 

 distinguish it from the rest of the sandy surface. 

 The plaintive note ceases at once. She must have 

 alighted somewhat by chance, since the most prac- 

 tised eye could not distinguish one spot from another 



