for study to Washington. Later in the year, after the larvæ had abandoned their hibernating chambers, Mr. Ehrhorn supplied us with partly developed larvæ in the terminals of the twigs, and still later pupa, together with field notes supplementing or confirming our breeding records.

Some of the twigs containing the young hibernating larvæ were, during the winter, fastened to peach trees growing in the entomological nursery attached to the insectary. Most of the larvæ in these twigs had been killed by a predaceous mite, and some few, perhaps, died as a consequence of the drying up of the twigs, but a considerable number of them wintered safely and ultimately entered the new shoots in the early spring and completed their development. With this material we were enabled to study their habits out of doors under natural conditions, following the species carefully through two generations and into the commencement of a third, as will be detailed below. By the end of August our working stock died out and we were unable to secure fresh supplies. The material was taken care of and notes were kept for the most part by Mr. Theo. Pergande, to whose skill and care is due much of the success of the breeding experiments.

Mr. Craw's report of the facts discovered by Mr. Ehrhorn is in the form of a brief note, and at the wish of Mr. Ehrhorn the more careful investigation of the insect herewith presented was undertaken by this Division. After the completion of the MS. of this paper the account of this insect by Mr. A. B. Cordley was received (Bul. 45, Oregon Exper. Station'), which is chiefly interesting as confirming the belief that the twig-borer and the strawberry crown-borer are probably distinct insects.

ORIGIN AND DISTRIBUTION.

The twig-borer is apparently an Old World species, and probably a very ancient enemy of the peach, with little doubt coming with this fruit from eastern Asia. It was described in Europe by Zeller in 1839 and in this country by Clemens, as Anarsia pruinella, in 1860. Clemens's species was afterwards shown to be identical with the European lineatella. As an important injurious insect in this country, attention was first drawn to it about 1872 by both Glover and Saunders, the report of the former being the first published. Glover's report describes excessive damage by it as a twig borer in young peach orchards in Maryland, and Saunders's report, while relating chiefly to marked injury by a crown-borer in strawberry beds (now known to be a different insect), refers also to injury to the peach twigs in Ontario. Considerable damage from the true twig-borer was reported some years later by Prof. J. H. Comstock as occurring in Virginia and in the District of Columbia, in connection with which the peculiar fruit-inhabiting

'The substance of this paper, with some additions, was republished in the report of the proceedings of the ninth annual meeting of the Association of Economic Entomologists (Bul. No. 9, n. s., U. S. Dept. Agric., Div. Entom.).

brood is first recorded. Later the insect was made the subject of an article by Dr. J. A. Lintner, in which it is reported to have occasioned damage to peaches in several localities in the State of New York. We also have accounts by Prof. C. V. Riley of injury to strawberry plants in Illinois, referred by him to Anarsia lineatella, and also articles on this insect particularly as a strawberry miner by Prof. S. A. Forbes. Very great damage to peaches in Kent and Sussex counties, Del., is later reported by Riley and Howard.

On the Pacific slope record is made of injury by it to various stone fruits by Mr. Coquillett, and later similar damage is reported in a letter from Mr. Knight, of Vancouver. We have also the results of the investigations by Mr. Ehrhorn in California, reported by Mr. Craw, and the recently published account by Mr. Cordley relative to the insect as affecting peaches and prunes in Oregon, and also in strawberry beds--a similar but undoubtedly distinct insect.

In addition to these more important published accounts, injury from the twig-borer has been often recognized and reported in later years. Nearly all these reports refer to the injury to twigs of stone fruits and very few to damage to strawberries, the strawberry-infesting insect either being more rare or less often observed. The records of this Department show the presence of the twig-borer in at least twelve States, and give a range which indicates that it is practically as widespread in this country as is the culture of its principal food plant.

If not already cosmopolitan in distribution the twig-borer is rapidly becoming so, and will probably follow the peach and other stone fruits wherever they are cultivated, especially as its peculiar hibernating habit greatly facilitates its distribution in nursery stock.

It is at times a very injurious insect, and is often notably abundant and destructive in such important peach districts as those of Maryland, Delaware, and Virginia. In California and elsewhere on the Pacific slope its injuries have a wider range, including, as indicated, the apricot, almond, nectarine, prune, pear, and perhaps other fruits, in addition to the peach. In California it is listed as one of the three or four worst insect pests occurring in the State. In Washington as many as 100 larvæ, or instances of damage to as many twigs, have been counted on a single tree.

HISTORY AND HABITS.

The fall brood of larvæ discovered by Mr. Ehrhorn may be taken as a convenient starting point in the life history of the twig-borer. In the fall, as reported by Mr. Ehrhorn (Craw), they appear as very small larvæ, living and working in the spongy bark chiefly at the crotches of the branches of the peach, and he surmises that they are from eggs deposited in these situations. Here the larvae are supposed to grow slowly until the new growth appears in the spring, when they leave. their cells in the bark and enter the new shoots. It is stated, also, that frequently the larva are nearly full grown when they attack the

young growth. The later brood is said to attack the fruit near the stems. The occurrence of the larvæ during the winter in the situations noted is also thought to explain the fact frequently noted that the under and inside twigs, being the more accessible, suffer the most, while the exterior and topmost branches escape.

Our later studies confirm, in the main, Mr. Ehrhorn's conclusions as to the habits of the larvæ. That the larvæ make any essential growth in the winter, however, is probably a wrong inference, as will be shown later, and the nearly full grown larvæ referred to were doubtless individuals that were wandering from one point to another, and had merely reached nearly full growth before they were observed.

Both in the orchards of California and by means of the abundant material received at this office we have been enabled to make a careful

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study of the hibernating galleries or chambers of the young larvæ. These occur not only in the crotches of the smaller and sometimes quite large branches, but many of the larvæ utilize the roughened bark at any point. They burrow into the bark for a short distance, penetrating little more than the upper superficial layer, and form slightly elongated chambers (fig. 1 c), which are linea with white silk and the opening afterwards closed. The location of the larvæ may be readily recognized by the little masses of projecting excrement or comminuted bark at the entrance to the burrows (fig. 1 a, b). The size of the burrow and the fact of its being lined with silk precludes the idea that the larvæ feed in the fall or during hibernation, except perhaps in the mere operation of excavating the chamber.

FIG. 1.-Anarisa lineatella: a, twig of peach, showing in crotch minute masses of chewed bark above larval chambers; b, same much enlarged; c, a lar

val cell with contained larva, much enlarged; d, dorsal view of young larva, more enlarged (origi

nal).

The young larva, as taken from the burrow, is not above 2 millimeters long, and is of a general yellow color, with the head and cervical and anal plates dark brown, almost black (fig. 1 d).

While in their winter quarters the larvæ are subject to the attacks of predaceous mites, and many of them are destroyed by this means, as will be later noted. They are also occasionally parasitized by a chalcidid fly.

Early in April the larvæ begin to abandon their hibernating quarters and attack the new leaf shoots, but some individuals were found in the crotches by Mr. Ehrhorn as late as April 21. The damage becomes noticeable, as a rule, at the time the shoots are from one-half inch to 2 inches in length, or, more properly speaking, mere clusters of newly expanded leaves.

Glover's account of their working downward in the old twigs from the terminal buds before the starting of the leaves in April apparently can not be questioned, but seems not to be the normal course, as shown by the observations since made.

In our experience, the larvæ begin to migrate only after the new foliage has begun to put out, and they attack the new shoots at any point, generally, however, from one-half inch to an inch from the apex, either near or in the crotch formed by the leaf petiole and the stem. The longest burrow observed was 13 inches and the shortest one-fourth inch. Sometimes the burrow extends about one-eighth inch above the the entrance, and occasionally the larvae simply eat into the shoot as far as the pith and then go elsewhere. The larvæ are seemingly restless and not easily satisfied, and are continually moving from one shoot to another, and are most active travelers. In this way a single larva may destroy or injure several shoots before reaching maturity, thus greatly increasing the damage.

Professor Comstock's observations on the habits of the larvæ in the young shoots are slightly at variance with the above. He says the larvæ puncture the shoots at the base, eating them off completely, the severed twigs remaining attached to the branch by the guminy substance which exudes from the wound. This particular form of injury we have not noted.

FIG. 2.-Anarsia lineatella: a, new shoot of peach withering from attacks of larva; b, larva enlarged; c, pupa enlarged (original).

When working in the succulent new growth the larvæ bores rather rapidly, sufficiently so at least to excavate a burrow two-thirds of its length in an hour. The length of time spent by the hibernated larvæ in coming to full growth in the green shoots is comparatively short, not exceeding ten to fifteen days.

In California and also in Washington the larvae begin transforming to pupa in the latter part of April, and the moths of the first brood emerge. throughout May.

The adult larva tapers strongly toward either end, and attains a length of three-eighths to a half-inch, or slightly more when in motion. It is of a dull reddish-brown color, the reddish color predominating before maturity and the latter after maturity, and the head, and the cervical and anal shields are dark brown or almost black. The space between the segments is noticeably light colored, and especially between the second and third thoracic segments. The hairs are long and spring singly from minute tubercles. Other details of structural features are shown in the illustration (fig. 2b).

In confinement the larva on reaching full growth spins a scanty web,

in no sense a cocoon, in the leaves and rubbish about the trees, or on the trees in the dried and shriveled leaves of the injured shoots, or it attaches itself exposed on the twigs or bark. After thus securing itself the larva immediately pupates, becoming a brown, rather robust, chrysalis (fig. 2, c, d). In midsummer these transformations are very quickly accomplished. A larva, for example, which webbed up June 29, pupated July 1, and the adult emerged July 8.

Mr. Ehrhorn states that it is very difficult to find the pupa in orchards as the larvæ hide in all sorts of places, as in crotches of the branches, between dried leaves, and about small peaches likely to drop off.

The chrysalis stage lasts from seven to ten days, and the moths of the first brood begin to appear early in May and continue to emerge through

FIG. 3.-Anarsia lineatella: a, moth with spread wings; b and c, same with wings closed illus trating position normally assumed-all much enlarged (original).

out this month and into June in the latitude of Washington.

The adult moth is less than a quarter of an inch in length, expanding a little more than half an inch, and is of a beautiful dark-gray color, with darker spots on the forewings, as indicated in the illustration (fig.3). It is a handsome insect and has a peculiar way of resting with its palpi bent back over its head and its antennæ laid closely down on the wings. The description of the insect by Clemens is reproduced:

A. pruniella.-Head and face pale gray; thorax dark gray. Labial palpi dark fuscous externally and pale gray at the end; terminal joint gray, dusted with dark fuscous. Antennæ grayish annulated with dark brown. Forewings gray, dusted with blackish brown, with a few blackish brown spots along the costa, the largest in the middle, and short blackish-brown streaks on the median nervure, subcostal, in the fold and one or two at the tip of the wing; cilia fuscous gray. Hind wings fuscous gray; cilia gray, tinted with yellowish. (Proc. Acad. Nat. Sc., Phila., 1860, p. 169.)

The egg-laying habits of this insect up to this time not having been discovered and for the fall brood even being merely a matter of conjecture, special effort was made to get the facts concerning this feature of the life history. A number of moths reared in the Insectary were confined about May 10 with peach twigs eight to ten inches in length, of this year's growth. The material was unfortunately not examined for too long a time, but on May 28 it was found that many eggs had been deposited on these peach twigs, an egg having been placed apparently just above the base of the petiole of nearly every leaf.

examined most of the eggs had hatched and the larvæ had entered the