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ville. New Smyrna, St. Petersburg, and Daytona were also suggested, but the time available was not sufficient, on account of the difficulty of making good railroad connections.

Citrus pests in Florida.

The principal pest of citrus fruits in Florida is the orange white fly (Aleyrodes citri). Associated with this insect there is in many localities another species called the cloudy-wing white fly (Aleyrodes nubifera, Berger), which was studied and described by Dr. E. W. Berger, Entomologist to the Florida Agricultural Experi- ment Station. In addition to these, another species, Aleyrodes howardi, has been found to seriously attack oranges in a few localities. This latter has been known as a pest of citrus trees in Cuba, but has only recently been recorded in Florida.

Aleyrodes citri is by far the most abundant of the white flies, and is the most difficult to control, largely on account of its power for rapid increase in numbers, and the great variety of non-citrus plants on which it can live.

The injury caused by this pest is most generally ascribed to the effects of the sooty mould or black blight. That is to say, black blight makes very vigorous growth wherever white fly is established, and when the attack of white fly is very severe, the black blight covers fruit, leaves, and bark with such a dense layer of growth as to seriously interfere with the functions of assimilation, and also to necessitate the washing of the fruit before packing.

The attacks of white fly do not appear to injure the leaves of the plants to the same extent that the purple scale does in the West Indies. The position of each group of purple scale on leaf of orange or lime in the West Indies is indicated by a discoloured spot, but no such indication of the presence of white fly was noticed in Florida. Although the attacks of white fly result in loss of vigour of the trees, and reduced yields of fruit, I did not see any trees in the dying condition so often seen in West Indian lime cultivations where scrious attacks of purple scale have been experienced.

The purple scale (Lepidosaphes beckii) and Glover's scale (L. gloceri) occur in Florida on citrus trees, but I saw no signs of a serious attack by these insects. Both these scales are known in the West Indies, the former (L. beckii) being the principal pest of limes in Domínica and Montserrat.

The Florida red scale (Chrysomphalus ficus) is fairly abundant, but is not usually

a serious pest. This scale also occurs in the West Indies.

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The orange rust mite (Phytophus oleivorus) occurs in Florida, producing russet oranges and "silvery grape fruit, and lemons, but I saw no evidence of serious attack in any of the groves I visited. This mite also occurs in the West Indies, but is not sufficiently abundant to be considered a pest.

The orange dog (larva of Papilio_cresphontes) sometimes eats the leaves of orange trees, but is not often a pest in Florida. It is reported to be more trouble- some in Cuba. There are several species of plant bugs (Hemiptera) which injure the ripening orange and tangerine fruits causing them to drop. The injury from these insects is due to the punctures made by the sucking mouth parts, and is similar to that observed in the Botanic Station at Dominica and reported from Nevis, which is due to a lepidopterous insect. The insects concerned in causing this injury and loss are the cotton stainer (D. suturellus), a green plant bug (Nezara sp. or spp.), a brown bug (possibly Euschites), and several others.

Amount of damage by citrus pests.

Severe attacks of white fly often result in a loss equal to 50 per cent. or more of the crop, the injury to the trees and the expense of washing the fruit necessitated by the presence of black blight, not being taken into account in this estimate. In many cases the attacks of this insect render orange cultivation unprofitable, but this does not usually happen when cultivation and fertilization of the groves receive proper attention.

The purple and long scales cause a considerable amount of injury to the trees, and in addition they are the source of great expense in the preparation of fruit for market. These scales often occur on the fruit, and even though they are removed by hard scrubbing, the fruit often sells at much less than fruit which was grown clean so that the difference in price and the cost of cleaning are losses due to the scale.

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The rust mite is said to be fairly abundant certain parts of the State. grower told me that it is a common practice to apply sulphur once or twice each

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season as a precaution. The sulphur is sprayed on in a mixture with water, or applied dry mixed in equal parts with lime. This mixture is applied from the hand broadcast over the trees, in the same way that seed is sown in the ground. The best time for applying the dry mixture is, of course, when the leaves are wet with dew or rain.

Control of citrus pests.

The insect pests of citrus in Florida have been controlled by fumigating, by spraying, and by means of natural enemies.

The work of fumigating has been the subject of extended investigations by the Bureau of Entomology of the United States Department of Agriculture, through experts and special agents stationed at Orlando. Results of a great deal of this work were published in Bulletin No. 76, of the Bureau of Entomology, entitled Fumigation for the Citrus White Fly, as adapted to Florida conditions," by A. W. Morrill, Ph.D., 1908. The report also gives results of spraying with insecticides for white fly and scale insects.

Natural enemies of white fly and scale insects.

As already stated, the principal citrus pest is the citrus white fly (Aleyrodes citri, R. & H.). Other species of white fly are the cloudy wing white fly (A. nubifera, Berger) and Howard's white fly (A. howardii).

"In addition to these there are the purple scale (L. beckii), the long, or glover's, scale (L. gloveri), and the Florida red scale (Chrysomphalus ficus).

The principal enemies of the white flies are fungoid. Their names and the dates

of their discovery on white fly in Florida are given herewith:-

Attacking white fly:

Red fungus (Aschersonia aleyrodis, Webber), 1893. Yellow (Aschersonia flaco-citrino, P. Henn), 1893.

Brown fungus (Aegeritis webberi, Fawcett), 1896.

Cinnamon fungus (Verticillium heterocladum, Penzig), 1907.

White fringe fungus (Microcera sp.) 1907.

White fringe fungus (Sporotrichum),

Red-headed fungus (Sphaerostilbe coccophila), 1903.

Attacking scale insects:-

Red-headed fungus (Sphaerostilbe coccophila). White-headed fungus (Ophionectria coccicola).

Black fungus (Myriangium duriaei, Mont).

From this it will be seen that the red headed fungus attacks both white fly and

scales, while the white headed and the black fungi attack only scale insects.

I saw in the groves visited, the citrus white fly (A. citri), the cloudy wing white

ily (A. nubifera), and the purple scale (L. beckii). These were all attacked by fungi,

and apparently well controlled in nearly every instance. I saw all the species of fungus attacking white fly and the red headed fungus on the purple scale.

The fungus, as the word is commonly used, refers to the red aschersonia, as that is the principal fungus on the principal pest; the other species are ordinarily designated by their common names.

The red aschersonia in full possession of a badly white fly-infested tree is a most remarkable and conspicuous sight. Every leaf, and seemingly every bit of the under surface of every leaf is taken up by the large, red, fungus pustules. This is the most conspicuous and the most effective of all the fungus parasites of the white fly. The brown fungus is very useful, and it is very abundant in certain localities. This parasite has the power of sending out its mycelial hyphae in search of other insects, and these growths sometimes extend over the leaf, down the petiole to the twig, and up on to other leaves. This habit is another method of spreading, in addition to the distribution of spores.

The yellow fungus makes its best and most rapid development on the cloudy wing white fly (A. nubifera).

The degree of control of the white fly by the fungi was remarkable; on some trees from 93-98 per cent. of the fly were estimated to be killed, and in most groves the proportion probably higher than 60 per cent.

The source of infection, and the conditions under which the fungus grew were various.