42 



KNOWLEDGE 



[Februaky 1, 1894. 



for the fact that some of the stinging insects are amongst 

 the commonest of the common, and that enormous numbers 

 of specimens of them are to be found, we might, in con- 

 sideration of the small proportion of the total number of 

 kinds that are thus harmful, expect not very frequently to 

 meet with any that would on this score justify distrust. 



In the above list of non-stingers, the only ones that call 

 for additional remark are the dragon flies. These large, 

 rapacious, and usually powerful insects have, unfortu- 

 nately, acquired a very bad name, and have a widely 

 extended reputation for stinging, which is, however, 

 nothing more than mere tradition, and has no foimdation 

 in fact. The popular prejudice against them is crystallized 

 in the common names of some species, such as horse- 

 stingers and devil's darning needles. The long, thin body, 

 which is often twisted about as if in search for an object 

 to attack, is, no doubt, partly responsible for the origination 

 of the idea of their veuomousness. Nevertheless, the idea is 

 absolutely incorrect ; as one writer has said : " Li both its 

 states of water and air, it can do everything wicked except 

 the one thing it is popularly supposed to do best, namely, 

 still;!." No stinging organs are possessed by any species, 

 and no power of doing direct injury to human kind exists 

 amongst them, so that no one need fear handling any kind of 

 dragon fly. The only possible suggestion of harm is in the 

 jaws of the larger kinds, these being powerful (relatively), 

 so that they can inflict a sharp pinch, but still not enough 

 to pierce the skin. 



Turning now to the Hymenoptera, as containing those 

 insects that most truly merit the epithet " stinging," we 

 find a special section of the order, to which the name of 

 Aculeata, or sting-bearers, has been given just because they 

 differ from the rest of their kindred by the possession of a 

 poisonous sting. This section contains several sub-divisions, 

 such as the ants.thefossores or diggingwasps, the true wasps, 

 both social and solitary, and the bees — these, too, including 

 both social and solitary species. As the sting is a modifica- 

 tion of the ovipositor, or instrument for depositing the eggs, 

 it is of course found only in the females ; hence, none of the 

 males of the above insects are able to defend themselves by 

 stinp;ing,but may all be handled with impunity. Their longer, 

 thinner body, and longer antenna; (Fig. 1) will often dis- 

 tinguish them ; but sometimes they are totally unlike their 

 partners, and therefore it is hardly possible to lay down 

 general directions for recognizing them. In those species 

 that are social the sting is carried not only by the true 

 females, who are often few in number, but also by that 

 curious and very numerous intermediate or third form 

 which is characteristic of social insects, viz., the workers, 

 who are a sort of abortive females. When, tlien, we speak 

 of being stung by wasps or by the hive bee, it is almost 

 invariably the workers who are the guilty parties. The 

 only female in a bee-hive is the queen, and she is not met 

 with in the open except at the time of swarming. Amongst 

 the wasps, the females, or queens, are more likely to be 

 met with, but they are far outnumbered by the workers. 

 Amongst the ants, a certain family, the luirmicida, are not 

 provided with a usable sting, but merely with a rudi- 

 mentary representative of that organ, though the poison 

 gland is well developed and contains poison in abundance ; 

 this they eject at their foes with considerable force and 

 to great distances, and as it-is of a strongly acid character, 

 it causes a smarting sensation on a sensitive skin, especially 

 if injected, as often happen?, into wounds already made 

 by their jaws. 



To illustrate the structure of the sting, we may take 

 the instrument as found in the largest species, as, for 

 example, a hive bee a humble bee (Fig. 2), or a wasp 

 (Fig. 8). The plan is the same in all, with differences of 



Flu. 2.— .Sting o( Humble Bi-e. Jlagnilieil 

 foui'ti'L'ii diametpvs. 



detail only. When not in use, the whole of the sting 

 apparatus is withdrawn between the pair of terminal plates 

 of the body, which 

 open like a mouth 

 to allow of its ex- 

 trusion. These 

 must be removed 

 before it can be 

 seen ; they can 

 easily be torn oft' 

 with a fine pair of 

 forceps. The sting 

 now stands revealed. 

 and its most pro- 

 minent part, which 

 wiU be at once de- 

 tected, is a strong 

 dart, straight or 

 curved according to 

 the species ; it is 

 grooved on its under 

 surface, and tapers 

 to a not very sharp 

 point. At its upper 

 end it is expanded 

 into a broad, pouch- 

 like body, and both 

 this and the greater 

 part of its narrower 

 continuation are 

 double- walled. 



Within the groove lie two long, narrow lancets, which 

 can be moved up and down in the dart, by running 

 along two projecting lines like rails, which extend from 

 top to bottom of the groove ; they are worked by levers 

 and muscles attached to their upper ends. The lancets 

 are notched at the free end with teeth that point back- 

 wards, like the end of a savage's spear ; throughout 

 their length they are hollow, but their cavity com- 

 municates with the exterior by a little channel amongst 

 the barbs. In communication with the pouch at the 

 top of the dart is a membranous tube, which is connected 

 with a thin-walled bag, the poison recejitacle. From 

 the upper end of this bag there passes a long, white, 

 thread-like, coiled tube, which soon divides into two 

 branches, each of about the same diameter as the undivided 

 tube, and these ultimately end blindly in little knob-like 

 swellings. The poison, which consists largely of formic 

 acid, is secreted within these tubes, and is poured from 

 them into the bag at the base of the sting, where it is 

 stored till required. Close by the base of the sting there 

 is a pair of hair-beset feelers, called collectively the sting- 

 sheath, and intended to assist in guiding the dart to a 

 suitable spot for attack. 



In the act of stinging, the dart and its feelers are first 

 thrust out between the terminal plates of the body, and 

 the dart is pressed against the object attacked, so as to 

 enter the skin ; the lancets are then slid along their rails 

 and pass out beyond the tip of the dart, thus making the 

 wound deeper ; at the same time poison passes from the 

 bag in which it is stored, down the groove in the dart, 

 and out at its extremity into the wounds ; but some also 

 finds its way into the interior of the lancets themselves, 

 and so out through the channel near their tip, and thus 

 into the wound at a deeper point. The recurved barbs on 

 the lancets and dart of course operate as a drag in any 

 attempt to withdraw the sting, and it is entirely a question 

 of the relative strength of resistance whether the sting 

 can be withdrawn or has to be left in the wound. Thus 



