Insect guide > Bees > Bumble Bee

Bumble Bee

Life History of a Bumble Bee
(Bombus fervidus Fabr.)
In our generalization on the habits of the true bees we said little about the bumble bees, preferring to let this typical life history speak for itself. The bumble bees belong to the group of social bees, although their communities are by no means as large or as perfect as those of the domesticated honey bee, nor in fact is the differentiation of the worker class so marked as with the honey bee. The workers, in fact, more nearly resemble the females and have few of the structural peculiarities which are so evident with the workers of the honey bee. The bumble bee worker stings severely and this fact makes the close study of their community life rather difficult.

Bombus fervidus, also called Bombus borealis, is a species which is common in Canada and the northeastern United States with something of a southern and western range and is a fairly typical bumble bee. At the approach of winter the old colonies fail, the workers and the drones, or males, die and only a few fertilized females remain alive. These hide themselves away in protected places, pass the winter in a torpid condition and when spring comes each one starts out to found a new colony. She collects moss or grass and pollen, seeks some depression in the field and begins a waxen cell under the grass or moss. Old nests of field mice are frequently used for this purpose. In this cell, which is stored with honey intermingled with a small quantity of pollen, is laid an egg and the formation of another cell begins at once. Along in July the nest will be found to contain a queen with a large number of workers of various sizes, as well as eggs and larvae in all stages of development.

Interesting observations upon this species have been made by Mr. F. V. Coville, who, although a famous botanist, ought to have been an entomologist, judging from his study of this insect. The precise duties of the different sized workers, according to this observer, are not evident but in general the larger ones attend to the mending of the covering of the nest and to the bringing in of honey, while the smaller ones for the most part do the inside housework, the wax patching and the nursing of the young. He never saw this nursing, as a matter of fact, done by a large or even a medium- sized bee. The eggs are laid several together in cavities in a mass of wax in which, however, are many pollen grains. The larvae after hatching remain encased in a shell of wax and soon become separated each from the other by a waxen wall. Here they are fed by a mixture of pollen and honey supplied them by a worker.

One of the smaller workers, which Coville has called the nurse bees, collects nectar and then pollen, preparing the mixture, and then goes to one of the larvae, which lie in circular form in their chamfers, and injects the brownish, fluid mixture through a small opening previously made, usually by another worker. This is greedily eaten by the larvae.

Whether the larvae of both females and workers are fed in the same manner and with the same mixture could not be decided, but it is known that in the honey bee the different kind of food influences the size and the function of the bees, a special food being used to develop queens. The larvae when full grown spin a silk cocoon and transform to pupae, in which stage they remain from two to three weeks and then transform to perfect bumble bees. The bees emerge from the cocoon after gnawing a lid about its apex.

As soon as the bee has left, the other workers cut away the upper half of the cell and remove the debris, and the part which is left furnishes a receptacle for nectar and honey as it is brought into the nest.

In early August, all the bees up to this time having been workers with the exception of the original queen, females, or queens, and males, or drones, begin to emerge. Within a few days both sexes leave the old nest and do not return.

The method adopted by Coville for the study of this species is an easy and convenient one and is worthy of description. A box about three inches deep and large enough to contain a nest (a good-sized cigar-box will do) was provided with a glass cover and a small hole was cut in the side. In this box in the early summer a nest taken from the field was placed and the aperture was closed for a day. The box was then fitted in below a window-sash so that the bees could come and go on the outside without annoying the observer, who remained in the room. In collecting the nest, which had been found during the day, the observer started for the field just before dark, after all the bees were in, provided with a cigar-box, a bottle of chloroform, a pair of forceps and a gauze-covered, wide-mouthed bottle. He approached the nest, poured a little chloroform over it, waited until the humming had ceased, opened the top of the nest, picked out the bees with the forceps and put them in the bottle, the nest with the "comb" being placed in the cigar-box. The bees revive after being placed in the permanent box, and the chloroform, if used moderately, does not kill the larvae.

The study of the life of a colony of bumble bees will be found to be a very interesting one, especially if observations are made upon the parasites and guest insects, or inquilines, which are frequently found in these nests. Many interesting points as to unimportant habits, especially as they bear upon the question of inherited instinct or intelligence, may be observed in this way. For example, these bees are very cleanly in their habits. Their faeces are always deposited in a particular place outside the nest.

Some of the guest bees frequently found in bumble bee nests belong to the genus Apathus, or Psithyrus, as it is now called. These bees resemble bumble bees so closely that it is difficult to distinguish between them and they live apparently in perfect harmony with bumble bees, but are lazy and use the food of the industrious bumble bees, both when adult and when in the larval condition. Bumble bees resent the introduction of one of these guest bees into their nest, but the intruder seems to have very pleasant manners for the alarm and resentment occasioned by his or her presence soon dies away and an amicable relationship succeeds. Whether the guest bee and its larvae consume so much food (they undoubtedly bring in some themselves) that they endanger the health of the colony of bumblebees is a disputed point.