large number of living forms await study from a similar point of view.

If we determine accurately the work of an individual and multiply this by the number of individuals, we have an expression of the species as a force in nature. Hence it is true, in general, that the commoner or more numerous a species is, the more important its biological work. We accordingly begin this series of dynamic studies with one of the commonest of American animals.

Of the ten species of Bufonida now recognized in the United States B. 1. americanus has the widest range, which includes almost the entire continent of North America east of the Rocky Mountains. It is, therefore, probably the most valuable type of the group.

The insect problem, further, is one of the most important in the entire field of American natural history. It finds partial expression in the annual tax of $795,100,000 which insects impose upon our agricultural resources. This is a rigidly conservative estimate made by the department of agriculture and does not include costs of abating annoyance or losses of household goods or those occasioned by spread of human disease. A large proportion of this loss might be most economically prevented by a reasonable knowledge and utilization of insectivorous animals. With all our books, bulletins and talk about it, we have scarcely made a practical beginning in this direction as a people.

In seeking animal allies to aid in the solution of the insect problem we should choose those which will do the work required most effectively and at the same time present the fewest objectionable features. A good many birds are efficient destroyers of insects, but become injurious if their numbers are unduly increased. Many insects are parasitic and predaceous, but, in general, their breeding or regulation is beyond human control. Clearly an animal to be depended upon to hold insects in check should be one which man can breed in any desired numbers and, on account of the enormous reproductive possibilities of insects, a form which he can in

crease rapidly. We may do much by way of increase of insectivorous birds, and even bats may prove valuable allies. We may be grateful for the help of predaceous and parastic insects, and good work has been done in importing parasites of foreign insect pests, but clearly we need all the assistance we can find; and all the above agencies are scarcely controllable enough to be depended

upon.

For an insectivorous animal which conforms to every requirement of the situation, ease of control and rapid increase, non-injurious, in any numbers, an active feeder in abundance and a patient faster in scarcity, the toad stands probably first on the list among American insectivorous animals. Experiments are now being carried on also with the bob white or American quail with every prospect that this form may prove of equal, if not superior, efficiency, and it will carry added values, in food, sport and weed-seed destruction; but this species is rapidly being exterminated from a large portion of its former range, and it will require a long time for methods of propagation and protection to be worked out and become generally known.

A good deal of unnecessary balancing of accounts has been done of late in attempting to calculate the economic value of species from analysis of the foods. In some cases this has yielded results of some value, but, in general, they have been misleading. Even a small percentage of the gross food of a hawk or shrike, for example, if it consists of a valuable species, might render the predaceous species injurious. In the case of beneficial insects, excepting the honey bee which is under human control, if a species will destroy all the injurious insects, it detracts little or nothing from its efficiency, if it take the beneficial insects as well. This principle applies particularly to the toad, which takes everything in the form of an insect, worm or slug that comes in its way.

Instead of filling its stomach four times in twenty-four hours, as Kirkland estimated, Mr. Miller finds that the toad takes but a single meal a day. This is no discredit

to the efficiency of the species. It means, simply, that we should require four times as many to do the work, and, with the number of eggs produced, this offers no difficulty.

Given a pond or even a small pool insured against drying up during the late spring and early summer, and from which natural enemies are eliminated, toads will breed in any desired numbers up to the limits of insect food supply. It would probably, however, be diffi-. cult or even impossible to find a single farm in the United States or Canada, although suffering severely from depredations of insects pests-not even the agricultural experiment station farms-which makes any provision whatever for the breeding of toads. In fact, reports so far gathered reveal the fact that farms in the agricultural states of Indiana, Ohio and Illinois are almost entirely destitute of the species. It is probably safe to infer that the toad has been exterminated already from a considerable portion of the cultivated land in the agricultural states. Is this an inevitable result of draining land, and modern methods of tillage? If this be true, can any changes or adjustments be made which will permit the increase of the species? Will the value of the toad's work warrant anything of the kind? Would it pay to establish special breeding places like our present fish hatcheries, or possibly in connection with them?

In order to answer these and many other questions we must have the data of the life and work of the species. To gather these in a manner, if possible, complete enough to serve as a guide and basis for practical action is the purpose of Mr. Miller's work.

THE AMERICAN TOAD (Bufo lentiginosus Americanus

LeConte)

The ancestors of the Bufonida first appear as fossils in the Oeningen beds below the Miocene Tertiary strata. The group now has a wide range, being found in all parts of the temperate and torrid world with the exception of Australia and the oceanic islands. The greatest number of species is found in the torrid regions. The

Bufondiæ are represented by nine genera and more than a hundred species. Bufo takes its origin in the Sonoran subregion, i. e., the southwestern part of the United States. It is the only genus found in the United States and is represented by ten species, most of which belong to the southern states. The species lentiginosus and its varieties are found throughout the eastern part of the United States and Canada. Two varieties, americanus and fowleri, share this region (Massachusetts).

Jordan and Cope class the American toad along with Fowler's as a variety of Bufo lentiginosus.1

My object in this work is to give as completely as possible the entire life and work of one species as normally lived in its own environment. Observations were made continuously throughout the year on the species, Bufo lentiginosus americanus, the results of which are given under the heads, Spawning Habits and Seasons; Development, Habits, and Food; Hibernation; and Enemies.

I am indebted to Dr. C. F. Hodge for suggestions while collecting the data for this paper, also for valuable criticisms of the manuscript. He also kindly consented

to write the introduction. I wish also to thank Mr. F. E. Chidester for assisting me with the feeding-tests and in obtaining data on the daily life of the toad.

SPAWNING HABITS AND SEASONS

Observations were made for the springs of 1907 and 1908, but if not otherwise stated the data for this chapter refer to the spring of 1907. Mention is made of 1908 when this season varies from that of 1907.

Toads were first seen in 1907 on the twenty-eighth of March and on the thirteenth of April in 1908. An adult male was found in the water on the night of March 29, 1907, but was so numb that he could not give the usual chirp when picked up. From March 29 to April 21 there was a decided drop in the temperature and toads

1 More recently Miss Dickerson has given these toads specific distinction, i. e., Bufo americanus and Bufo fowleri.

were not seen again until the night of the twenty-second of April, on which date seven males were found trilling in pond no. 1.2 Eight days later when the migration to the ponds reached its maximum, mated pairs were abundant on the streets and elsewhere on their way to the water. Trilling began in 1908 on the twenty-third of April and spawning on the twenty-fifth, ending May 13. The seven toads mentioned were the first heard trilling this season. They were sluggish and when taken up between the thumb and finger could not chirp, although they made the attempt.

The accompanying curves show the number of toads as well as the number of males and females that were found in pond no. 1 on the night of April 24 and succeeding nights (Fig. 1). Spawn was found here the twentyno. of Toads.

FIG. 1. Curves showing the number of toads in pond, No. 1, during the spawning season. No. 1, Females. No. 2, Males. No. 3, Total.

sixth. The males were most active on this and the night of the twenty-ninth. On these dates they were trilling vigorously and actively swimming about. If they saw an object moving they swam to it with all possible speed. When it was a male, which was usually the case, he was seized, but loosed as soon as he chirped. They even came

2 This pond is located at the foot of a small steep hill in a pine grove in Park Avenue Place within a hundred yards of a large permanent pond. It is V-shaped, not more than fifteen feet wide by fifty feet long, and during the spawning season was about eighteen inches deep. For the most part it is filled with leaves, some water plants and debris from a near-by dumping ground. Rains are its only source of supply and it goes dry in summer.