464 MEANS OF DEFENCE OF INSECTS. 



a true Troglodyte, always in its cell under ground, biting the stems at 

 their base, which falling bring thus their foliage within its reach. ^ 



The habitations of insects are also usually places of retreat, which 

 secure them from many of their enemies : but I have so fully enlarged 

 upon this subject on a former occasion, that it would be superfluous to do 

 more than mention it here. 



1 am now to lay before you some examples of the contrivances, requir- 

 ing skill and ingenuity, by which our busy animals occasionally defend 

 themselves from the designs and attack of their foes. Of these I have 

 already detailed to you many instances, which I shall not here repeat ; 

 my history therefore will not be very proUx. I observed in my account 

 of the societies of wasps, that 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 destroyers of their combs, 

 Galleria mellonella and its associates, will endeavor to make their way 

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

 nels pacing about with their antennae extended, and alternately directed 

 to the riiiht and left. In the mean time the moths flutter round the 

 entrance ; and it is curious to see with what art they know how to profit 

 of the disadvantage that the bees, which cannot discern objects but in a 

 strong light, labor 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 antennae. These bees upon 

 guard in the night are frequently heard to utter a very short low hum ; 

 but no sooner does any strange insect or enemy touch their antenna than 

 the guard is put into a commotion, and the hum becomes louder, resem- 

 bling that of bees when they fly, and the enemy is assailed by workers from 

 the interior 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 often barricade the entrance of their hive by a 

 thick wall made of wax and propolis. This wall is built immediately 

 behind and sometimes in the gateway, which it entirely stops up; but it 

 is itself pierced with an opening or two sufficient for the passage of one 

 or two workers. These fortifications are occasionally varied : sometimes 

 there is only one wall, as just described, the apertures of which are in 

 arcades, and placed in the upper part of the masonry. At others many 

 little bastions, one behind the other, are erected. Gateways masked by 

 the anterior walls, and not corresponding with those in them, are made in 

 the second line of building. These casemated gates are not constructed 

 by the bees without the most urgent necessity. When their danger is 

 present and pressing, and they are as it were compelled to seek some 

 preservative, they have recourse to this mode of defence^, which places 

 the instinct of these animals in a wonderfid light, and shows how well 

 they know how to adapt their proceedings to circumstances. Can this be 



> Fiih. Eiit. Sipt. Em. iii. 70. 200. « Huber, Now. Obs. ii. 412. 



» Ruber, Nauv. Obs. ii. 294. 



