Stinging Insects 



37 



25. 



Sting of a honey bee. Psn Sc, base of acid 

 poison gland; B Gl, alkaline poison gland; 

 Stn Pip, sting palpu Sh B, bulb of sting; 

 5/i A , basal arm ; Z,cr, lancets or darts; Shs, 

 shaft of sting. Modified from Snodgrass. 



like sting palpi. Comparative morphological as well as embryologi- 

 cal studies have clearly established that these three parts corres- 

 pond to the three pairs of 

 gonopophyses of the ovipositor 

 of more generalized insects. 



An examination of the inter- 

 nal structures (fig. 26) reveals 

 two distinct types of poison 

 glands, the acid-secreting and 

 the alkaline-secreting glands, 

 and a prominent poison reser- 

 voir. In addition, there is a 

 small pair of accessory struct- 

 ures which have been called lubricating glands, on account of the 

 supposed function of their product. The acid-secreting gland empties 

 into the distal end of the poison reservoir which in turn pours the 

 secretion into the muscular bxdb-like enlargement at the base of the 

 shaft. The alkaline secreting gland empties into the bulb ventrad 

 of the narrow neck of the reservoir. 



The poison is usually referred to as formic acid. That it is not so 

 easily explained has been repeatedly shown and is evidenced by the 

 presence of the two types of glands. Carlet maintains that the pro- 

 duct of either gland is in itself innocent, 

 — it is only when they are combined that 

 the toxic properties appear. 



The most detailed study of the poison 

 of the honey-bee is that of Josef Langer 

 (1897), who in the course of his work used 

 some 25,000 bees. Various methods , of 

 obtaining the active poison for experi- 

 mental pvurposes were used. For obtaining 

 the pure secretion, bees were held in the 

 fingers and compressed until the sting was 

 exserted, when a clear drop of the poison 

 was visible at its tip. This was then taken 

 up in a capillary tube or dilute solutions 

 obtained by dipping the tip of the sting into 

 a definite amount of distilled water. 

 An aqueous solution of the poison was more readily obtained by 

 pulling out the sting and poison sacs by means of forceps, and grinding 



26. Poison apparatus of a honey 

 bee. Modified from Snod- 

 grass. 



