WILD LIFE IN NEW ZEALAND

Otago Witness, Issue 3495, 8 March 1921, Page 54

WILD LIFE IN NEW ZEALAND

Hon. G. M. Thomson, F.L.S.

By the I

No. 108. The life-history of humble bees in Britain has been pretty fully worked out. In this country it is not much different, except for the change of seasons; but it has to be remembered that the conditions in Otago and Southland, which approximate to those of the Old Country, are different from those of the extreme north, where the bees do not, strictly speaking, hibernate at all. First, however, we may consider what species we have in New Zealand ; they are four. The commonest bee in Otago is Bombus terrestris, the large earth humble bee, the queen of which is a black bee, with a band of deep yellow across the front %i the thorax, and another on the second segment of the abdomen; the tail is tawny. Its length is 20-22 mm., and the of the wings 40-42 mm. The workers are much smaller, only 11-17 mm. long. The males are 14-16 mm., and the expanse 30-33 mm. In these two last forms the tail js tawny-white. Closely allied to this species is B. lucorum, the small earth humble bee, a somewhat smaller species, with lemon-yellow bands, and a pure white tail. In both these soecies the nests in summer contain about 200 workers. B. terrestris is a sharp-tempered bee, which will attack anyone disturbing its nest, and will hover round it for some time ready to sting anything that approaches it. The third species is B. ruderatus, the large garden humble bee. This insect is about the same size as B. terrestris, the queens being 21-23 mm. long, with expanse 40-43 mm., and the others corresponding. Is is a black bee, usually with a bright yellow narrow band at the front, and another behind the thorax, and the tail white. But entirely black specimens are fairly common. These are not distinct varieties, for the same queen often produces both banded and black bees. Sladen savs of this species that the workers and males in the same nest are sharply dimorphic—either quite black or quite banded, — while the queens show every degree of variation. He suggests that the proportion of the varieties -produced by each queen

follows* Mendel’s law. This would be a good subject for research for any student to follow up. It is not difficult to attract queen bees to occupy artificial nests, and the development of the colonies is easily studied. B. hortorum, the small garden humble bee, bears the same relation to B. ruderatus that B. lucorum does to B. terrestris; it is a smaller species similarly marked. Their nests are not so populous as those of the first-named group. These two last-named species are relatively long-trunked; they are the bees which directly fertilise the red clover. B. terrestris and B. lucorum can only reach the pollen, but not the nectar. The trunk of a queen of B. hortorum is about as long as its body, or about gin. If one holds a specimen of B. terrestris in one hand, directly facing one, and a B. hortorum in the other, it will be seen that the face of the former is far shorter than of the latter. In 1906 the Canterbury Agricultural and Pastoral Association, thinking the wrong kinds of bees had been introduced into the country, got Mr Sladen to send out three more shipments and 143 bees were liberated. These were all B. hortorum and B. lapidarius, the stone humble bee, eksily recognised by its bright red tail. None of the latter, however, have been seen since. Now, as to the life-history of these insects. About January or February in each year the young colonies of bees produce young queens, as well as workers and males. The queen is fertilised soon after her liberation from the nest, and as soon as tins takes place she seeks for a bed in which to make her nest. In Britain this is for her long, winter sleep, but in New Zealand her hibernation is only partial. B. terrestris usually selects the ground for a burrow, B. ruderatus sometimes in the ground, B. lucorum and B. hortorum commonly in moss or heaps of rubbish. The young queens usually leave the nest for good on their first day of flight, filling themselves with honey before they leave. As the weather grows cold in autumn they fold their legs and bend as in death, sinking into a deep torpor from which they are not easily roused. This winter sleep in Britain lasts about nine months, and the. bees are not awake again till late spring or early summer. But in New Zealand it is probable that no hibernation takes place in some northern districts, and that in southern ones it is only partial. I have, recorded bees from this part of the Dominion during every month of the wear. Now, our winter cold in Otago is often fairly severe ; the mean winter temperature being 41deg Fahrenheit, and the mean minimum only 35deg. Yet on any fine day, even in midwinter, and following a night s frost, the queens may be seen out in the sunshine. They are feeding, too. Thus in one season alone I have recorded them from the sth of July onwards. In August thev were seen on four days on Laurustimis, Hakea. and broad bean flowers In September on eight days on flowers of plirm trees, gooseberries." currants, rosemary. Acacia araniata (for pollen only), pink heath (Erica sp.b white crocus, white hyacinth, white pansy,, violet, wallflower, narcissus, marigold. Virginian stock, Arabia, and Salvia Grahami. On several of these days the ground was white with hoar frost in the early morning, yet the bees were out in the heat of the day. It may he that this comparative mildness of climate is one cause of the diminution of numbers of the bees. It mav be that those which venture out do not always find shelter in time. Tt is, however most probable. tha.t the chief factor in keeping down the increase of these insects is the not infrequent cold and wet spring weather which prevails in New Zealand. Tu Europe humble bees have several enemies which keep them in check

shrews, field mice, and aits attacking their nests and eating the young brood. The caterpillar of the humble bee wax-moth (Aphomia sociella) feeds upon the brood and everything else in the nest. Several larvae of flies and beetles also live on the brood. The most remarkable enemy, however, is a species of usurper bee, which is so like the true humble bee that only an expert can t-ell the difference. Each species of Bombus has its own species of Psithyrus, whiclf breeds in its nest. Here is Mr Sladen’s description of this remarkable case of parasitism. 1 ‘lnvestigation showed that it is the practise of the psithyrus female to enter the nest of the Bombus, to sting the queen to death, and then to get the poor workers to rear her young instead of their own brothers and sisters. The way in which she proceeds in order to ensure the success of her atrocious work has all the appearance of a cunning pcan, cleverly conceived and carried out by one who not only is a mistress of the crime. of murder, but also knows how to commit it at the most advantageous time for herself and her future children, compelling the poor orphans she creates to become her willing slaves.” Humble bees have several other enemies, but none of them have been brought to New Zealand, and this maker it all the more difficult to account for the relatively small numbers of the insects, now that they are so well established here. ( Headers of Darwin’s intensely interesting Origin of Species”-—and all Nature-lovers should know the book—will remember the statement made there, on the authority of Colonel Newman, that humble bees’ nests are more numerous near small towns than in the open country, because cats are more common about towns, and these keep down the field-mice, which are the greatest enemies of the bees. Mr Sladen does not think the statement quite correct as a general rule, though it may be the case m particular localities. Common mice (not field-mice) abound in our fields, and may account for some nests of bees, hut they are not counted among the enemies of these insects in Britain. Starlings and tuis have been seen catching humbfe bees and carrying them off to their nests. According to a writer in the Akaroa Mail the. tuis were seen catching the bees and taking the honev-bags from them, as small boys clo in the Old Country. This recalls two passages from the “Midsummer Night’s Dream.” In one Titania enjoins the fairies to find delights for Bottom : Feed! him with apric-ocks and dewberries, With purple grapes, green figs, and mulberries ; Tho honey-bags steal from the humble-bees, And for night-tapers crop their waxen thighs And light them at the fiery glow-worm’s eyes. Later on Bottom wakes up and finds the fairies round him, whom he thus addresses : “Mounsieur Cobweb, good mounsieur, get you your weapons in your hand, and kill me a red-hipped humble bee on the top of a thistle; and, good mounsieur, bring me the honey-bag. Do not fret yourself too much ni the action, mounsieur; and, good mounsieur, have a care the honey-bag break not; I would be loath to have you overflown with a honey-bag, signior.” e really do not know the cause of the diminution m numbers of the humble be-63 in this country, where all the conditions seem at first sight so favourable to their increase, and for the present must attribute it. to the climatic conditions, cold, w et spring weather being particularly fatal to the queens when about to found new r colonies. Before following out the life history of the humble bee in detail we may note some of the interesting facts which" everyone can see for themselves. These bees feed on all introduced flowers which yield them nectar or pollen, but especially on those with long tubes which are not accessible to hive-bees. I have not found that they visit many of the indigenous flowers, though perhaps other observers can expand my list. They are very fond of the flowers of the native fuchsia, or konini, frequently sucking out the nectar left by honey-birds or tuis, through the portions of the tube torn open by the birds. They nave also been recorded on Veronica ellipon __ many large hybrid veronicas, ngaio (Mvoporuni laetum), and muehlenbeckia. Mr Philpott found them on the flowers of celmisia on the Hunter Mountains at a height of 4500 ft, and to get to this open upland country irom the Monovyai fiats they had to traverse or pass thiough about- six miles of Nothofagus forest. When dead humble bees are met with the bodies are usually found to be infested with numbers of small red mites. I thought at one time, and Mr W. W. Smith shared my belief, that these were responsible for the death of the bees. But Mr Sladen says thev are quite harmless, and feed on the wax and bee-food, as well as or. any refuse about the nests. Among the local enemies I omitted to mention that Air Smith has frequently found numbers of dead humble bees with a small puncture either in their thorax or abdomen. On one occasion he saw a specimen of B. terrestris seized by a large native robber-fly, Asiluc varius, which pulled it to the ground, and killed it in a few seconds by sucking out the viscera.