MEANS or DEFENCli: OF INStCTS. 263 



designs and attack of their foes. Of tliese 1 have already 

 detailed to you many instances, which I shall not here 

 repeat ; my history therefore will not be very prolix. — I 

 observed in my account of the societies of wasps, diat 

 they place sentinels at the mouth of their nests. The 

 same precaution is taken by the hive-bees, particularly 

 in the night, when they may expect that the great de- 

 stroyers of their combs, Gcdlerla melloneila and its 

 associates % will endeavour to make their way into the 

 hive. Observe them by moonlight, and you will see the 

 sentinels pacing about with their antenna; extended, and 

 alternately directed to the right and left. In the mean 

 time the moths flutter round the entrance ; and it is cu- 

 rious to see with what art they know how to profit of 

 the disadvantage that the bees, which cannot discern ob- 

 jects but in a strong light, labour under at that time. 

 But should they touch a moth with these organs of nice 

 sensation, it falls an immediate victim to their just anger. 

 The moth, however, seeks to glide between the sentinels, 

 avoiding with the utmost caution, as if she were sensible 

 that her safety depended upon it, all contact with their 

 antenna?. These bees upon guard in the night, are fre- 

 quently heard to utter a very short low hum ; but no 

 sooner does any strange insect or enemy touch their an- 

 tenna;, than the guard is put into a commotion, and the 

 hum becomes louder, resembling that of bees when they 

 fly, and the enemy is assailed by workers from the inte- 

 rior of the hive ''. 



To defend themselves from the death's-head hawk- 

 moth, they have recourse to a different proceeding. In 

 seasons in which they are annoyed by this animal, they 

 " Vol. 1. 165. " Huber, Nouv. Oba.n. 'WZ. 



