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ENTOMOLOGICAL FEATURES OF 1924. The season of 1924, like that of 1923, was abnormal and began with cool moist weather followed by a drought. Very little rain fell between July 1 and October 1, and the drought of 1924 was even more severe than that of 1923.
Some of the outstanding features of the season were the disappearance in injurious numbers of the apple and thorn skeletonizer, which was so abundant in 1923, the greater increase in the Oriental peach moth, and further infestations of the European corn borer in six towns along the coast.
There has been no serious spread of the gipsy moth, though a few additional towns were found infested by the Federal scouts. Because it was not possible for the Federal men to scout the entire southern portions of New Haven and Middlesex Counties and it was not known whether or not they were infested, some 23 additional towns were included in the quarantined area.
Though a watch has been kept, not a single nest of the browntail moth has been seen in Connecticut since 1919.
FRUIT INSECTS. The tent caterpillar, Malacosoma americana Fabr., continued to be abundant throughout the State, though particularly so in the western portion. Every 10 or 12 years this insect reaches its period of greatest abundance, being comparatively scarce half way between these high periods, probably checked by natural enemies.
The fall canker worm, Alsophila pometaria Harris, which is present locally somewhere in the State nearly every year was very abundant in Greenwich and Stamford in early summer and stripped many kinds of deciduous trees, apple, elm, hickory and oak being particularly injured. A few caterpillars were found feeding on maple, but the trees were not stripped. Around New Haven, this insect was present in destructive numbers, but no injury was observed or reports of injury received from outside of New Haven and Fairfield Counties. See Plate XXXII.
The apple and thorn skeletonizer, Hemerophila pariana Clerck, which was so prominent and was responsible for so many brown apple trees in 1923, was conspicuous by its absence in 1924. Evidences of its presence could be found in nearly every orchard by the slight skeletonization on terminal leaves, but its work had been arrested, the caterpillars were not there and no particular damage had been done. Apparently natural enemies have been unusually prompt in subduing this insect.
On the other hand, the Oriental peach moth, Laspeyresia molesta Busck, was much more in evidence than in 1923, and wormy peaches were rather common in Fairfield and New Haven Counties, late in the season. If this pest continues to spread, its control will
become one of our most important problems. Further details will be found elsewhere in this Report.
The European red mite, Paratetranychus pilosus Can. and Fanz., was less abundant in 1924 than in 1923, and no serious injury from its attacks was brought to my attention. Eggs were present in winter in many orchards, especially in the northern portion of the State, but spraying the dormant trees with miscible oils was generally practiced with satisfactory results. Probably the wet spring may have reduced the numbers of this pest, for it was not evident later in the season in most orchards, and I have yet to learn of a single case where it was considered necessary to give a summer spray in 1924 for its control.
The sinuate pear borer, Agrilus sinuatus Oliv., continues to spread eastward and it causes some injury at first. This European insect first appeared in the United States in New Jersey some 20 years ago, caused serious injury there for a few years, but is now not regarded as a serious pest. It was first recognized in Connecticut in 1917 at Norwalk, and the writer observed its destructive work in a pear orchard in Stamford in 1920. In May 1924, after the receipt of specimens, Mr. Zappe visited the premises of Mr. W. T. Camp, Shelton, where several old trees had been nearly killed by this insect, and had been removed. Other pear trees in the vicinity had been more or less injured. Probably the best treatment consists in removing and burning the seriously injured trees and branches; then cut out the borers from the remaining portion and coat the bark with a wash of lime-sulphur and lead arsenate to repel the beetles and possibly kill the larvae when they enter the bark. The foliage should also be kept covered with lead arsenate during May and June to kill the adult beetles which feed there before laying eggs. If the trees are kept well fertilized and cultivated, they will be more apt to outgrow injury caused by this insect.
Males of the lime tree winter moth, Erannis tiliaria Harris, were fairly abundant flying about lights in the fall, and the greenishyellow black-spotted females were found on tree trunks. The caterpillars feed upon apple trees and on elm, linden and other trees in the woodlands. The caterpillars feed at about the same time as canker worms, but are larger and there is danger that they will cause some damage the coming season. Spraying with lead arsenate is the remedy. Further information will be found on page 311 of this Report.
The light or false apple red bug, Lygidea mendax Reut., was rather less abundant than usual, though it caused some injury locally here and there. Fruit injured by it in Wallingford and Danbury was brought to our attention.
The rosy apple aphis, Anuraphis roseus Baker, was rather scarce in most orchards early in the season, though egg-infested twigs were received in March from Middlebury, Middlefield, Milford, Cannondale and South Glastonbury. On June 9 it was observed in Stamford and Wallingford. By June 24, it was present in moderate numbers in nearly every orchard and injury was caused by it in some cases.
The green apple aphid, Aphis pomi DeGeer, hatched in April, and on the 25th at Milford there was an average of about one aphid per bud, but on May 22, practically all aphids had disappeared in the orchards under observation in Milford, New Haven, Hamden and Cheshire.
The woolly apple aphid, Eriosoma lanigerum Hausm., seems to be present in nearly every orchard though it is uncertain just how much injury is caused by it. Further information regarding this insect may be found on page 308 of this Report.
The pear psylla, Psylla pyricola Foerster, was abundant on pear trees in Wallingford, Southington, Hebron and other places, though in one garden it was less common then for several years. It can be controlled by dormant sprays of nicotine solution and soap, of lime-sulphur and of miscible oils. Sometimes it may be necessary to give a summer treatment either as a spray or dust to prevent blackening of the fruit by later broods.
Leafhoppers were abundant on apple foliage, May 22, in Milford, Hamden and Cheshire.
The plum curculio, Conotrachelus nenuphar Herbst, yet remains one of the important pests of the apple orchard and series of experiments have given results which though somewhat contradictory, seem to indicate that thorough applications of lead arsenate at the pink, calyx and two weeks spray, will give fair control. Scarcely any additional benefit could be seen from the seven day treatment. Dr. Garman and Mr. Zappe have already worked two seasons on the five-year program for the study and control of this insect in apple orchards.
The currant aphid, Myzus ribis Linn., was present as usual on currant bushes, and specimens were received from Hebron on May 9, and from Colchester on May 16.
A particularly striking case of injured currant twigs attacked by the currant stem girdler, Janus integer Nort., was brought to the Station from Woodbridge in April.
VEGETABLE INSECTS. Most of the common insect pests of the vegetable garden were present in 1924, but on account of the backwardness of the season, appeared two or three weeks later than usual. The absence of rain during July, August and September was favorable to some kinds of insect life and unfavorable to plant growth.
The usual amount of injury was caused by cutworms. During June, reports were received of injury to nearly all kinds of vegetable plants in New Haven County, but probably such injuries were not confined to one county but occurred all over the State. A more general use of poisoned bran mash would certainly reduce the losses occasioned annually by cutworms.
The stalk borer, Papai pema nitela Guen., as a pest is fairly constant each year, and tunnels in nearly all kinds of herbaceous stems, even in weeds. It attacks plants here and there, but never are all stems attacked. Growers pay little attention to it, until the stems have been injured. Control measures other than destroying the infested stalks are not successful. Probably on account of the wide distribution of this insect and the character of the injury which it causes, few reports come to this office. However, specimens were received in potato from Terryville, August 7, and in rhubarb from Wethersfield, August 12.
The cucumber or potato flea beetle, Epitrix cucumeris Harris, is usually a garden pest each year, and in 1924, was abundant in many fields attacking potato, tomato, egg-plant, cucumber and squash. Reports were received of the abundance of this insect at Woodstock, Brooklyn, Killingly, Cheshire, North Haven, Southington, Plainville and Stratford in June. In the potato field at the Station Farm, Mount Carmel, the beetles were very abundant on the untreated rows, moderately abundant on the rows treated with Niagara potato dust, and much less so on the rows heavily sprayed with Bordeaux mixture and lead arsenate. About 300 gallons per acre was applied on August 2.
On July 18, specimens were received from Shelton of the silverstriped webworm, Crambus praefectellus Zinck., which eats into the side of the corn plant near the surface of the ground. Occasionally this insect is the cause of considerable injury, and in 1919, an acre field of corn in New Haven was destroyed by it.
Only limited numbers of the corn ear worm, Chloridea obsoleta Fabr., were present on the ears of late maturing corn. Specimens were received on October 17, from Milford, where in one field about five per cent. of the ears were injured. On the whole, this insect did little damage.
The western corn root worm, Diabrotica longicornis Say, is present in Connecticut, where it was found in Granby feeding on the petals of flowers. More information regarding this insect may be found under Notes on Miscellaneous Insects in this Report.
One of the tortoise beetles, Deloyala clavata Fabr., feeding on potato, was received from Norwalk, July 25. Only rarely are these beetles sufficiently abundant to cause injury, and lead arsenate is an effective remedy, as it is also on foliage for the blister beetles, of which there are several species.
The spinach leaf-miner, Pegomyia hyoscyami Panzer, was present around New Haven, Stratford and Westport, in moderate numbers, but Mr. Friend failed to find a badly infested field suitable for a line of experiments which had been planned.
The cabbage maggot, Hylemyia brassicae Bouche, was scarce in Litchfield County, but was reported as causing much injury in New Haven, Hamden, Vernon, Hebron and Ellington late in June. By June 26, it had attacked cabbage and cauliflower in Ridgefield, Bethel and Danbury. Common control measures are tarted paper disks, and the corrosive sublimate treatment, but Mr. Friend obtained good control by trapping the adult flies. His experiments are given in detail on page 314 of this Report.
The green cabbage worm, Pontia rapae Linn., though fairly abundant at the Station Farm, Mount Carmel, was generally scarce and caused little damage. In most cases no poison was applied. The cabbage looper, Autographa brassicae Riley, was more prevalent than the green cabbage worm, and injured the leaves and heads by riddling them with holes.
Another pest, the parsnip leaf-miner, Acidia fratria Loew, was discovered in Wethersfield, July 12. The infestation was slight though the mines were rather extensive in the leaves. The species has before been taken in Connecticut, but we have never observed its injury until 1924. The life history and control measures have not been worked out, and therefore we cannot recommend any treatment.
The onion thrips, Thrips tabaci Linde., was found injuring a field of onion sets at Wethersfield. The plants had not been wilted, and on July 16 and 21, nicotine was applied as described on another page of this Report.
Asparagus beetles, Crioceris asparagi Linn., and C. 12-punctata Linn., were reported as being troublesome at Suffield, June 9; Black Hall, June 18; Riverton, June 24, and Danbury and Norwalk, June 26. As a rule, spraying with lead arsenate after the cutting season is over, and on young beds will control these beetles. Some growers report success with applications of nicotine sulphate.
Aphids of certain kinds were present in usual numbers and caused the usual amount of damage. On August 6, the turnip aphid, Aphis pseudobrassicae Davis, was brought to the Station from East Haven, where it had killed and seriously injured turnip plants in a small field. The pea aphid, Illinoia pisi Kalt., was not generally troublesome, though it did injure certain fields, and made its appearance very late in the season. It was reported from Thomaston and Danbury on June 24, and a heavy infestation at Ridgefield on June 26. A small field in New Haven was found infested on June 19, and a few days later a small portion of it was dusted with nicotine by Messrs. Friend and Walden. The results are given on page 319 of this Report. The potato aphid, Macrosiphum solanifolii Ashm., was rather scarce and only one thoroughly infested field in Branford, was observed on July 1, but the aphids were heavily parasitized. Slight infestations were observed in Westville and Highwood on June 30, but there was no infestation of the potato fields at the Station Farm at Mount Carmel. The cabbage aphid, Brevicoryne brassicae Linn., was common through