out nursery stock north, south, east, and west, and a certain proportion of this stock carried upon it the San José scale. The scale was not recognized until the summer of 1893, when I found it upon some pears from Charlottesville, Va. Since that time my investigations have resulted in the ascertaining of nearly two hundred points in which the scale has established itself and become destructive. Not one of these points is in territory which clearly belongs to the transition life zone, and yet who can question the statement that thousands and thousands of young trees bearing this scale must have been sold to fruit growers located within this region, and have been planted by them.

Even considering the San José scale by itself, the evidence is entitled to great consideration, and to my mind is sufficiently strong to form a basis for a guarded prediction. But it must be further remembered that this is but a single instance among very many known to us, and that it is upon the mass of facts we are basing our knowledge of the indications of the general laws which govern the geographical distribution of species.

There are, however, localities in your State where the San José scale and the West Indian peach scale are liable to do great damage, and it thus becomes necessary for fruit growers to inform themselves about both species. I have now in proof a complete bulletin referring to the whole subject of the San José scale, which it will give me pleasure to send to any members of this Society who care to apply for it, so that it will not be necessary here to treat of this insect at any great length.

The life history of all scale insects may be briefly summarized very much as follows:

The eggs are laid by the adult female either immediately beneath her own body or at its posterior extremity. Certain species do not lay eggs, but give birth to living young, as do the plant lice. This abnormal habit is not characteristic of any particular group of forms, but is found with individual species in one or more genera. The young, on hatching from the eggs, are active, six-legged, mite-like creatures, which crawl rapidly away from the body of the mother, wander out upon the new and tender growth of the tree, and there settle, pushing their beaks through the outer tissue of the leaf or twig and feeding upon the sap. Even in this early stage the male insect can be distinguished from the female by certain differences in structure. As

a general thing, the female casts its skin from three to five times before reaching the adult condition, and beginning to lay eggs or give birth to young. With each successive molt the insect increases in size and becomes usually more convex in form. Its legs and antennæ become proportionately reduced, and its eyes become smaller and are finally lost. As a general thing it is incapable of moving itself after the second molt, from the spot where it has fixed itself, although certain species crawl throughout life. The adult female insect, then, is a motionless, degraded, wingless, and, for all practical purposes, legless and eyeless creature. In the armored scales she is absolutely legless and eyeless. The mouth parts, through which she derives nourishment, remain functional, and have enlarged from molt to molt. Her body becomes swollen with eggs or young, and as soon as these are laid or born she dies.

The life of the male differs radically from that of the female. Up to the second molt the life history is practically parallel in both sexes, but after this period the male larva transforms to a pupa, in which the organs of the perfectly developed, fledged insect become apparent. This change may be undergone within a cocoon or under a male scale. The adult male, which emerges from the pupa at about the time when the female becomes full grown, is an active and rather highly organized creature, with two broad, functional wings and long vibrating antennæ. The legs are also long and stout. The hind wings are absent, and are replaced by rather long tubercles, to the end of each of which is articulated a strong bristle, hooked at the tip, the tip fitting into a pocket on the hind border of the wings. The eyes of the male insect are very large and strongly faceted. The mouth parts are entirely absent, their place being taken by supplementary eye spots. The function of the male insect is simply to fertilize the female, and it then dies. The number of generations annually, among bark lice, differs so widely with different forms that no general statement can be made.

As a general rule scale insects have been divided, both from the classificatory standpoint and from the standpoint of practical remedial treatment, into those which are armored or secrete scales over their bodies, and those which are naked and have no differentiated scale. From the practical standpoint, however, this division is of no great use, since even the so-called naked

scale insects become so hard-bodied, and their integument is composed of such solid chitine, that they are practically as resistant to the action of washes as are those species which have a dense scale of wax. A better classification, when we are considering the matter of remedies, is to divide the group into those species which give birth to living young and those which lay eggs. The object of this division will be at once apparent. Those scale insects which give birth to living young, drop a number of young per day for a comparatively long period. Those first hatched. become resistant to the action of washes within a few days, so that at no one time do we have even a majority of the insects in the young and unprotected condition in which washes, weak enough to do no damage to the foliage, will kill them. With the scale insects which lay eggs, on the contrary, there is a more or less definite hatching period. In other words, all the eggs in a given generation hatch at approximately the same time, and the majority of the young are in a condition to be killed by weak washes at about the same time. The species that give birth to living young can therefore be treated to advantage only in the winter, when there will be no danger of injuring the foliage of the trees by the action of washes which are strong enough to kill the insects under their scales. The best example of this class is the San José scale. The egg-laying species, as exemplified by the common oyster-shell barklouse of the apple, pass the winter (most of them) in the egg condition under the old mother scales. They hatch, approximately all together, the latter part of May or in June, and at this critical time may be destroyed by the dilute kerosene emulsion.

Let us hurriedly, then, take up a number of species, all of which Massachusetts fruit growers should know. But a few words need be said about each, since the illustrations on the screen and the specimens which I shall exhibit afterwards, will convey a more definite idea of the appearance of the insects than any words of description.

The lecturer next gave a brief account of the following species, of some of which engravings from the publications of the Department of Agriculture are here presented :

The San José scale (Aspidiotus perniciosus), Fig. 1.

Oyster shell barklouse of the apple (Mytilaspis pomorum), Fig. 2.

FIG. 1.Aspidiotus perniciosus (The San José or Pernicious Scale), on pear fruit and twig, with enlarged male and female scales. (From U.S. Dept. Agric.)

FIG. 2.Mytilaspis pomorum (The Oyster-shell Bark Louse): a, female scale from below, showing eggs; b, same from above-greatly enlarged; c, female scales. (From U.S. Dept. Agric.)