BLACK WIDOW SPIDERS

By M. V. Walker,
Associate Park Naturalist,
Crater Lake National Park.

It was not difficult for the biologically minded observer to see that Mrs. Latrodectus had not long been a widow, for there was every indication that there was to be an increase in her family. Father was not to be present for the blessed event, for he had been taken for a bit of nourishment in a time of famine, and had passed quietly from the household. He would not be missed, for once a female Black Widow Spider is fertilized she is fertilized for life, and need never mate again. The males are devoured simply for their food value in case of famine, and not because the female prefers to be a widow.

Mrs. Latrodectus survived this depression period, and again good times loomed ahead. Feed became more abundant and her girth increased until she was barely able to be about; in fact, there were times when she made the mistake of climbing down to the lower portion of her web-dwelling and it was only with great effort that she was able to regain her seat at the top of the stairs, where she preferred to reside, serene and proud as a queen. Finally the great day arrived. She fashioned a cover for the nest, fastening it securely by strong but delicate hangers. Under this protecting roof she proceeded to deposit a large number of white, glossy eggs. She wrapped them in a delicate white blanket, and tied it all securely to the cover of the nest. The main event was over, so she retreated a short distance--viewed the incubator with some concern, and then settled down to wait and watch for results.

Mrs. Latrodectus continued to wait and watch, and eat; and a second time it became necessary to fashion a nest, and into this were deposited more white and glossy eggs, to be wrapped in a white blanket and tied securely by strong threads of silky white. Again Mrs. Latrodectus viewed the nest at some distance and retreated to wait and watch. As before, waiting and watching was interspersed with periods of feasting, and before long it was necessary to fashion a third nest, then a fourth. But Mrs. Latrodectus was not discouraged. She began to show quite an interest in the first pear-shaped nest that had been fashioned some days ago. Although it remained white on the outside, the entire center of the structure was getting dark. The quivering of the hammock indicated that there was some sort of movement within the nest. The next few days were filled with expectancy, and finally, if one had been watching carefully, he would have seen that a tiny opening was made near the top of the nest, and there followed a single file procession. One by one they came through this tiny pin hole, until the entire enclosure which was the home of Mrs. Latrodectus, was a wriggling mass of gray and striped bodies, about 150 of them.

Although Mrs. Latrodectus had constructed a number of fine strands for moving around within the enclosure, it seemed that the little Latrodectuses were very proud of their ability to make strong threads of their own over which they might explore this new world. It was not long until the entire place was a mass of tiny threads, for the spiders' activities were confined solely to the interior of a specimen fish bowl. It was on May 15, 1939, that Mrs. Latrodectus was captured and placed in the jar for observation, and it was on June 2, 1939, that she fashioned the first nest and filled it with eggs. The second nest was made on June 9, the third on June 18, and the fourth on June 28. On June 30, the first young emerged.

The family had now increased to such size that it was something of a problem to supply sufficient food. The main diet of Mrs. Latrodectus consisted of crickets, grasshoppers, flies, moths, and butterflies. She was rather cautious in all her actions, and although she must have been extremely hungry on numerous occasions, she always went through a definite procedure in preparing her victim for his demise. When a cricket was dropped into the jar it would be placed in the small fish bowl that formed the bottom half of the apartment. Mrs. Latrodectus seemed to prefer to live upstairs, for she was usually to be seen hanging upside down near the top of the specimen jar, exposing the red hour-glass design on her abdomen. The cricket would soon become entangled in the strong webs that were scattered throughout the bottom jar, and would kick and jump in an attempt to free himself. The shaking of the web network seemed to be the first signal to Mrs. Latrodectus that a foreigner was making an approach, and she would immediately start searching through the maze of threads for the object that was causing the disturbance. She moved quickly but cautiously, and soon approached the intruder. She seemed always to size up the situation for a brief second; plan her attack, then turn about face--and the battle was on.

Although Mrs. Latrodectus is credited with a most virulent type of poison, (one drop is equal to twenty drops of rattlesnake venom) she preferred to do her fighting in a hit-and-run manner. First she started throwing webs about the long hind legs of the invader. She went at this with a vengence, for the white frothy material from her spinnerets shot out in little droplets, and her long hind legs moved so rapidly that they could hardly be seen. It was only a matter of seconds until the strong hind legs of the cricket were enmeshed with dozens of strands of web, and the more he kicked, the tighter became the hobble. If the cricket became motionless for a few seconds, Mrs. Latrodectus would cease her warfare and retreat a short distance and turn around and look the situation over, but the slightest movement by the victim was the signal for a right about face and another bombardment of sticky threads.

This was continued until the cricket was tied up in such a manner that he could hardly move; at least his movements were so restricted that Mrs. Latrodectus felt safe in approaching closer, and this she did with caution. She moved slowly and deliberately toward the victim; then with the suddenness of a bullet she opened her tiny jaws and sank her fangs into the big joint of the hind leg of the cricket, and then just as quickly retreated. This was usually the signal for violent struggling by the cricket, she was not completely exhausted but just resting. This would bring forth another attack of web throwing by Mrs. Latrodectus, until no movement could be detected, at which time she would again approach very cautiously and perhaps selecting the other large hind leg of the victim, again sink her fangs into the big joint. This would be repeated until Mrs. Latrodectus was quite sure the victim was securely tied, and perhaps partly paralyzed; at least there was little chance for the cricket to do any fighting.

Then Mrs. Latrodectus did a rather strange thing. Her food supply was securely tied, but apparently she preferred to do her feasting upstairs, for she started pulling, or hoisting the cricket up and up into the jar. She tied a big thread to a portion of the cricket and then with her long hind legs holding the thread, she climbed toward the top of the jar, pulling and tugging. Whenever she was able to hoist the victim a bit she tied the thread securely and went down to attach another hoist. This she repeated for minutes at a time, until finally the victim was tied securely near the top of the upper jar.

Mrs, Latrodectus was at last ready for her meal. There were evidently certain portions of the cricket which were considered delicacies, for she attached her mouth parts to the upper part of the head of the cricket, there to remain for hours at a time, evidently sucking the body juices from the victim. Nor was she to be deprived of her meal for just any little disturbance, for one might shake the jar violently, causing her to sway from side to side, yet she would cling with tenacity to the head of the cricket. After all the food was taken from the head, she then drained the food from the body of the cricket, leaving him as only a skeleton. Finally she cut the threads holding him up in the jar, letting him drop to the bottom.

When all the little Latrodectuses came into the world, her feeding habits were a bit changed, for as soon as she had secured her victim and had him neatly tied in the middle of the jar and started to feed on his delicious head parts, the little Latrodectuses proceeded to line up on the big femur and other body parts and try to get their share of nourishment. By the time Mrs. Latrodectus had got around to the less desirable portions, they had been completely drained. The youngsters grew so rapidly and soon developed such appetites that they turned from cricket femurs to more palatable morsels, their less fortunate brothers and sisters. The family was thereby quickly reduced in numbers, and it was but a few days until only 10 or 12 of the stronger were the sole reminders of a once happy family of 125 to 150.

Mrs. Latrodectus had not spent all her time feeding on cricket heads, but had continued to fashion nests and deposit eggs. By July 27, she had deposited eight cases in the jar and the first four had hatched, but of the approximately 500 young that had been brought forth, most were devoured by their more voracious brothers and sisters. From the first group several young females were beginning te show signs of growing up. There was no question but that the quarters were too confining, so Mrs. Latrodectus and her last four egg cases were transferred to a new apartment. After five more egg cases had been added to this jar, quarters again became crowded and she was transferred for the third time to a new apartment where she at once set about fashioning egg cases until four more had been produced, making in all a total of fourteen of these pear-shaped white hammocks of silky web.

Although Mrs. Latrodectus was kept busy with her own apartment, she often took time to glance back at the first place she had called home. It was then that she nearly burst with pride, for she could see that two of her daughters were nearly as large as she. They had lost their gray, striped, and spotted dresses, and had now put on fine black silky dresses with only the hour-glass design of brilliant red on the front. She could also see that several of the smaller ones had developed large bulbous knobs on the front of their heads. These knobs stuck out as if on short poles. These offspring she recognized as sons now quickly reaching their maturity.

But one day her heart was saddened when she chanced to glance over toward the first apartment, for there was only one daughter to be seen. This daughter had grown enormously during the past few days, and there now remained in the jar this one large female with two or three adult males, and a few tiny dwarfs whe were, apparently, not worth while even catching for food. It was only a few mornings later that Mrs. Latrodectus took occasion to glance over toward the first home, and it was then that she was shocked beyond description, for hanging near the top of the old apartment was a pear-shaped nest with a proud new mother guarding it zealously. Mrs. Latrodectus just had to take time out from her morning work to recall the events of the past few weeks. It was just fifty days ago that this daughter had entered the world. Things were certainly moving along, and one could never quite tell what the next day would bring. Just twenty-five days later old Mrs. Latrodectus was again surprised when she chanced to glance toward the first apartment for there she saw just dozens of little Latrodectuses clambering over the place. The thought suddenly struck her, why, she was a grandmother, and all in the course of a mere seventy-five days.

The summer and fall had passed, and winter was aproaching. As cooler weather set in, the Latrodectuses became less active and would often hang for days at a time upside down near the top of the apartment. The young in apartment two continued to grow and become mature, and the young in the apartment with old Mrs. Latrodectus also became quite as large as their mother, and perhaps considerably more virile, for on November 8, the observer's heart missed a beat when he saw that Old Mrs. Latrodectus had been securely tied up during the night by one of her own daughters. It was thus that a grand and glorious old lady passed from the world of the Latrodectuses.

There was no question however, but that the family was to carry on, for some of the children of young Mrs. Latrodectus had grown very rapidly, and there was now observed a number of developing females and males. Young Mrs. Latrodectus was moved to a new apartment, for during the late summer she had deposited three more cases of eggs, and this made the place a bit crowded. It was also realized that even young Mrs. Latrodectus might some night fall victim to one of the more active youngsters. Nothing of particular interest happened until January 25, 1940, when a large brown house spider in the apartment of young Mrs. Latrodectus caught her off guard and suddenly put her "on record", as far as the family genealogy was concerned.

All thoughts were now turned to the occupants of old apartment one, for here were the children and grand-children of the two Mrs. Latrodectuses. Only two daughters remained along with some four or five young sons which were quite mature. In order to avoid a catastrophe, one young female was removed to another apartment, leaving a single female in the first apartment. On February 20, 1940, the observer was brought to quick attention, for during the night Mrs. Latrodectus III had fashioned a pear-shaped nest of silky web and filled it with pearly white eggs. These eggs contain an even more potent poison than that produced in the poison glands of the female Black Widow. Extreme caution should be used in handling them. It would surely be a day worth recording when these young emerged, for they would be the great grand-children of Old Mrs. Latrodectus. But the weather was cold, and development slow, and it was not until April 24, 1940, that the first great grand-children worked their way through the tiny opening at the top of the nest, and found their way out into the world.

This apparently was the signal for a repetition of the entire series of events of the past year, for Mrs. Latrodectus III proceeded to deposit egg cases, and those continued to hatch the season.