March 1, 1894.] 



KNOWLEDGE. 



55 



FlO. 4. — Melliuns arvensis. 

 Magnified three diameters. 



centre of the under side of the prey. There is a good 

 anatomical reason for this ; in this position is placed the 

 central mass of the nervous system, and a sting so 

 directed as to pierce that important apparatus woiild no 

 doubt at once produce paralysis, while similar wounds 

 inflicted elsewhere would be followed by less serious 

 results. 



These are certainly marvellous facts, and indicate an 

 amazing degree of sagacity on the part of the insect. 

 But this is just the characteristic for which the aculeate 

 Hymenoptera, as a body, are, above all insects, celebrated ; 

 indeed, it is in this group that insect intelligence reaches 

 its highest grade of development. Numerous instances 

 of similar skill and pei'severance have been recorded by 

 English observers, and especially by Mr. F. Smith, one of 

 our earlier historians of these insects. Amongst other 



records may be noted 

 some curious facts which 

 he gives about one of our 

 commonest fossores, Mel- 

 Ihius arvensis, a shining 

 black-bodied insect with 

 yellow bands (Fig. 4), 

 which provisions its nest 

 with various kinds of 

 Diptera. He says : " It 

 is amusing to see four 

 or five females lie in wait 

 upon a patch of cow-dung, 

 until some luckless fly 

 settles on it ; when this happens, a cunning and gradual 

 approach is made. A sudden attempt would not succeed, 

 the fly is the insect of quicker flight ; therefore, a degree of 

 artifice is necessary. This is managed by running past 

 the victim slowly, and apparently in an unconcerned 

 manner, until the poor fly is caught unawares and carried 

 oft" by the Melliints to its burrow." A similar device is 

 adopted by prettily variegated, but small, species belonging 

 to the genus Od-i/belus. When the first fly has been 

 deposited, an egg is laid ; the necessary number of victims 

 are then soon secured, and the mother's task is complete. 

 But the matter is not always so simple ; there is the 

 instability of the English climate to be reckoned with, and 

 this may upset the calculations and multiply the anxieties 

 of even these lowly creatures ; for, as Mr. Smith adds, 

 " sometimes she is interrupted by rainy weather, and it 

 is some days ere she can store up the quantity required." 

 A larva which was found feeding became full-fed in ten 

 days ; in that time it devoured the softer parts of six flies 

 — the heads, the harder parts of the bodies, and the legs 

 being the parts left untouched. 



The same indefatigable observer, who spent many years 

 of his life m gaining a knowledge of the habits of the 

 aculeate Hymenoptera, records of a certain colony of a 

 jet black fossor (Tnjpoxylmi Hi/uIhs) which preys upon 

 spiders, that they had very sensibly constructed their 

 burrows in a bank of light earth just under a hawthorn 

 hedge which was tenanted by large numbers of small 

 spiders ; the hunters had therefoi'e only to rush out of 

 doors and flit up into the hedge in order to accomplish 

 the task of provisioning with the least possible expenditure 

 of time and energy. When the prey is small and gregarious, 

 it will be captured in a wholesale manner ; thus Mr. Smitli 

 states of another black species [Pemphredon liujubris), that 

 he has seen the female " settle on a rose-tree, and scraping 

 a number of aphides into a ball, fly oft" with it, carrying it 

 in front of its anterior legs and under its head." One of 

 our largest and most local species {I'ldlanthus tnamjtdum), 

 a black and yellow insect, actually preys upon bees, using 



i"ia. 5. — Tubular entrance to 

 nest of Odt/nerus, 



whatever kinds happen to be most abundant in the neigh- 

 bourhood of its nest, but showing a preference for the hive 

 bee. It is a bold-looking creature, but very slow to use 

 its sting upon human kind, although it has no difficulty 

 in overpowering the bees that constitute its prey. These 

 it catches by lying in wait amongst the flowers they 

 frequent, and pouncing on them as they are intent on 

 gathering honey. Seizing the bee with its jaws between 

 head and thorax, it at once inflicts a sting in the abdomen 

 and thus renders its victim powerless ; then grasping it 

 tight with jaws and legs, it flies off with its burden to its 

 nest. 



One of the most curious of the solitary wasps is that 

 called Eumenes conrctata. Like the rest of its tribe, it is 

 black, with yellow bands, but it may be at once distin- 

 guished by the long, thin stalk that attaches the strongly 

 pear-shaped abdomen to the thorax. This curious insect 

 constructs little globular cells of mud on the stalks of 

 heath plants. Each cell is the residence of one larva only, 

 and is provisioned with small caterpillars. Others of the 

 solitary wasps, belonging to the genus Odynerus, burrow 

 into banks, and arrange at the entrance of the burrow a 

 sort of cylindrical vestibule, made 

 of fragments of the surrounding 

 soil ; it thus appears as a tube 

 projecting from the mouth of the 

 burrow, and curving downwards 

 (Fig. 5). If the burrow be traced 

 to its end, cells will be reached, 

 which, when opened, display 

 piles of half-dead caterpillars 

 stored up for the young. Mr. T. R. Billups once foimd a 

 colony of one of these insects at Chertsey, the entrance 

 tubes of which were about an inch and a half long. On 

 opening one of the cells he found a truly bountiful pro- 

 vision, testifying to great industry on the part of the 

 collector ; as many as thirty-three small caterpillars of 

 moths, and four of saw-flies, all reduced to a semi-animate 

 condition by the stings they had received, composed the 

 lavish stock of this little larder. 



Notwithstanding their stings, the fossorial Hymenoptera 

 and solitary wasps have to suffer much at the hands of 

 parasites ; ichneumon flies, golden wasps, and a set of 

 dipterous flies {Tachinidm) , shaped rather like blue-bottles, 

 make more or less havoc amongst their larvse. Mr. 

 •J. E. Fletcher records having found in a damaged willow 

 tree a pile of small cocoons crowded together in a small 

 space. From a portion of this pile which he took home 

 he bred twenty-seven examples of a black fossor [Crabm 

 leucostoma), together with an ichneumon fly and a dipterous 

 fly belonging to the above family. As the cells of the 

 Crahro had been provisioned with small and delicate long- 

 legged flies, of a family quite distinct from that of the 

 parasites, the relics of four dift'erent kinds of insects had 

 thus become associated in one spot, thereby affording to 

 anyone who might find the collection after the insects 

 had deserted it, an interesting zoological puzzle to deter- 

 mine the mutual relations of the dift'erent members of the 

 company. Such associations of heterogeneous remains are 

 sometimes brought about by the practice that some of 

 these insects adopt of taking possession of the abandoned 

 burrows of other insects, instead of putting themselves to 

 the trouble of excavating their own. Thus Mr. Douglas 

 records having found examples of the above-named 

 Trypoxylon in the burrows of one of the bark-boring 

 beetles we recently described. Spiders had been stored in 

 the burrows as food, and one of the golden wasps was also 

 present asapai-asite upon the Trypoxylon. But in addition 

 to these, another species of Trypoxylon had also made its 



