CiRt unfl N i 104. United States Dcpan incut of Agriculture, BUREAU OF ENTOMOLOGY. L. O. HOWARD. Entomologist ami Chief of Bui THE COMMON BED SPIDER. (TrtrnniicliHM bimariilatu* ilnrvey. 1 B I'. H. Chittenden, 8c. D., In limn/I nf Truck Crop and Special Insect (nrcxtinatioii*. I \ l HOD1 i roHi . < )nc of ilif most troublesome of greenhouse pests is n minute, red- dish, spiderlike creature, known popularly as "red spider." It does very considerable damage in flower and vegetable gardens, and in greenhouses attains it- greatest destructiveness. It is particularly injurious to violets and roses, and attacks n great variety of other plants, including shade and fruit trees and some field crops. Beans, cowpeas, eggplant, cucumber, and tomato, especially when grown in hothouses, sustain much injury, while melon-, squash, and berries are subject to destructive attack. Red spiders are not true insects, in fact not even spiders, but arc more properly speaking, spinning mites. Since however, they are almost universally known as " red spiders," this term is retained. \ the won! "mite" indicates, these insects are extremely minute, and when they occur in ordinary numbers are not apt to lie noticed unless the leaves are carefully scrutinized. Attention, however, is certain to be drawn to them when they become excessively numerous, a- frequently happens in neglected greenhouses or out of door- during droughts in summer. Red spiders -pin thread-, hut do not. like true spiders, utilize them For climbing or for descending from a height. The threads -pun are 'xtremely line and scarcely perceptible to the unaided eye. hut a web ■ Until the year 1000 tlie common red spider, most often occurring in _ rbnically designated a- Tctranychu* tiim-iu* ].., n uame which !i - beeu rather Indiscriminately applied to all species of nil spiders, both in America ami abroad. B4T51 dr. i'*i of threads is frequently so dense as to form a tissue plainly visible at a little distance. Webs arc constructed upon the lower side of leave-. and attached here and there to projecting hair-, veins, or the edge- of the leave-. Within the webs thus formed the mites feed in their different stages, and the eggs are laid from which the young develop. DES< i;iitj\ i.. The general appearance of this red spider as seen under a micro- scope is well shown in figure 1. u. At h a greatly enlarged palpus of the same species is illustrated, and c shows the claw-, similarly enlarged. The length of full-grown individuals, including the palpus, i> about T) '„ inch (0.4 to 0.0 mm T. and the width about 1 fa inch ( 0.25 to 0.30 mm ), the thickness being 0.17 to 0.20 mm . The form is broadly oval, the width greatest in the anterior third of the body, back of the eyes, where the side:- are somewhat distended. The general color of the adult i> reddish. usually more or less tinged with yel- lowish or orange, and most specimen- have a dark spot on each side, due to the food contents of the body, from which the scientific name himaculatus (two-spotted) ha- been derived. Careful study of different individ- uals as they occur on garden vegetables and on horticultural and other plant - growing in the field with those taken fig. i.— The common rod spider m ar-eenhouses shows no appreciable (Tetraniicliu* bimaculatUB) : ". t <*> > t -» r -v- i \duit: 6, palpus; c, claws, a, differences. According to Mr. Nathan Greatly enlarged; b, c, still more Banks, specimens taken in Florida on enlarged. (After Banks.) r . Datura and at Washington, I). C, on violets are red. while those from Orono, Maine, and those from the District of Columbia on squash and peach, and on rose from Idaho, are greenish with more or less dark markings. The eggs are extremely minute, spherical, of variable diameter. glassy, and are scattered and loosely attached about the web-. The young are somewhat similar in appearance to the adults, but differ in having only three pairs of legs, while the adult has four pairs. DISTRIBUTION. This red spider is well distributed throughout the eastern Ohited States, and was identified as occurring a> far west a- Idaho in 1!>00. In 1002 it was recognized from Brighton. Wash.; in 1!>07 from south- [Or. 104] era California; and in 1908 at Brownsville, Tex., this lasl locality practically assuring its occurrence in Mexico. \ \ I I l:i 01 i Nil B1 . The red spider occurs in greenhouses throughout the year, and appears to be nt all times destructive it' permitted i«> propagate. I'tw plants are, in fact, free from its attack, and ii is found in mosl greenhouses. When only a few mites are present the plants seldom -how :in\ external evidences of injury, but as thej increase in number the leaves gradually turn paler and become yellowish and stunted, Mini soon the whole plant succumbs unless the proper remedies are applied. Cuttings or young rooted plum- are particularly subject to serious injury, and this is especially true in the spring. At this time the mites multiply rapidly, and unless plants are carefully watched they are apt to become so badly infested that it is only with extreme difficulty that they can be restored to their normal growing condition. The mites injure plants by suction, and when they occur in num- bers, which they almost assuredly do when plants are neglected, the vitality of the plants is slowly 1 n 1 1 surely reduced by the 1"-- of the juices, and in time ;ill of the plants 1 functions arc more or less deranged. In cases of severe attack, million- of red spiders can l>e found upon the foliage, and the webs, rarely observable at ordinary times, sometimes stretch from plant to plant, the mites passing rap- idly over them and congregating in -warm-. rooo pi w i s. The red spider is nearly omnivorous, attacking a wide range of both glabrous and hirsute plant- belonging to many families. It has been observed on plant- of the following li-t : Among greenhouse and other ornamental plant-, roses, violets, carnation- or pink-, mignon- ette, clematis, pelargonium, abutilon, fuschia, passiflora, manettia, bonvardia, feverfew, verbena, heliotrope, salvia or sage, morning- glory, moonflower, cypress-vine, phlox, chrysanthemum, calla, Easter lily, Boston smilax, mimulus, slipper flower (Calceolaria), canary bird {Tropaolium peregrinum) , thunbergia, wedding bells {Brug- mansia arborea), castor-oil plant. Asparagoides plumo*a, cuphea, godelia, sunflower, and aster. Of the plant- listed, violet- and roses are very susceptible to damage by the red spider, more especially when the plant- are growing under glass. if. as -.'.'m-i probable, Tt tranychus < m umeria >>r some >ther species described by Bolsduval (Entom. Horticole) is Identical with v. bimoculatus, ir is quite likely that this red spider is of foreign <>riirin and Introduced int«> the United st;itrs. which is true of a very large proportion <>f greenhouse and other Indoor Insects. |('ir. 104] Among truck and vegetable crops, leguminous giants are greatly injured, more especially beans, including Lima beans. Cucumbers and tomatoes grown in hothouses, cantaloupes or muskmelons, water- melons, and squash are also badly damaged. Eggplant, pepper, pepino {Solanum muricatum) , corn, cowpeas, raspberry, strawberry, beets, and celery are also subject to attack, but are not as a general ride very seriously injured. Of field crops infested other than those which have been mentioned are hops. hemp, peanut, and the groundnut or wild bean (Apios i pios ) . Trees grown for shade and for fruit are subject to attack and con- siderable injury is effected at times. The list of trees that have come under observation as subject to the greatest injury includes the Ken- tucky coffee tree (Gymnocladus canadensis), the hop tree (Ptelee trifoliata), pecan, ornamental sassafras, arborvitae, maple, horse- chestnut, and birch. INJURY To TRUCK CRnl's. Every year this species i- noted in considerable numbers on the underside of leaves of bean in and. about the District of Columbia. frequently causing great blotches and the withering of a large portion of the leaf. When the mites occur in such abundance it necessarily causes a drain on the vitality of the plant and a decrease in the pro- ductiveness of seed-pods if not of the seeds themselves. Still, as a rule, such injury is rarely noticed until comparatively late in the sea- son, in September and October. Similar injury has been reported in Georgia and South Carolina to all forms of beans — snap, butter, and Lima— as well as to cowpeas. In the same States injury has been reported to a variety of other truck crops. Writing in June, one of our correspondents stated that his cucumbers looked as if a blight were on them; another wrote: " A fine garden three weeks ago now looks as if a fire had struck it." INJURY TO TREES. Injury by the red spider to shade and fruit trees is insignificant, as a rule, compared with that which is accomplished by leaf-feeders such as caterpillars. Sometimes, however, very considerable defolia- tion is caused by the attack of this species. This was very noticeable during the summer of 1906, when the foliage of various shade trees in the city of Washington was injured. Attack was first observed during the third week in July and was manifested by the leaves hav- ing turned yellow on the upper surface. The leaves on the lower branches showed the presence of numerous feeding colonies The Kentucky coffee tree suffered most of all of our city trees. On one of these trees the leaves continued to drop throughout the remainder of July and August, but by September, partly owing to an unpre- cedented rainfall of three week-' duration, the mites were less in evi- [Cir. 104 j ,1,. ,,,,. Bn d many branches from which the leave* had fallen developed new clusters of fresh leave Two vears later it was noticed thai manj "I the lower branches which hail suffered most from defoliation \>\ the red spider were dead, i'i,. j Kentucky coffee tree, showing !>:in 1:1 1 defoliation bj the red spider on lower branches; upper branches bare pnt onl oew Original I without doubt owing t<> the attack of this insect. The accompanying illustration (tiir. 2) was taken after the new leave- had become well [Or. 104] 6 developed. Two or three weeks before thai time the lower half of the tree bore only ;i few leave-. This same form of injury was repeated in L908, the tree looking considerably worse than shown in figure 2. NATURAL ENEMIES. The predaceous and parasitic inseci enemies of the red spider, men- tioned below, were observed by the writer on the Kentucky coffee tree at Washington, I). C, during July and early August, VM'>. Scymnus punctum Lee, a very small black ladybird, was observed July 21, chiefly as a nearly full-grown larva, and was the most active natural enemy. At that time it was for the most part attached to the leaves for pupation, and a single pupa was found then and many a few days later. Nearly all the larva' had transformed and the beetles had begun to issue by the 1st of September. An illustrated account of this species was given by J. C. Duffey in 1891." Cecidomyia coccidarum Ckll. ( ?). — The larva of this small cecido- myiid fly was reared at Washington, where it Avas fairly abundant. It was secondary in importance only to the ladybird mentioned, as a destroyer of its red-spider host. With the hitter was reared a minute chalcis fly. Aphanogmus va- ripes Ashm.. a species recorded as parasitic on ceeidomyiids. Chrysopa ruflabris Burm., a lacewing fly. was also reared and the larva was observed in numbers attacking the red spider. Thrips sexmaculata Perg. has been recorded as an enemy of the red spider by Pergande B and by Duffey. METHODS oi' CONTROL. DIBECT REMEDIES. Eed spiders are more resistant to fumigation, either with tobacco or hydrocyanic-acid gas. than are aphides, thrips. and small forms of insects generally. Only a portion of these creatures are usually killed by the ordinary use of the gas in greenhouses — never more than 80 per cent, so far as our records go. The remainder may be stupefied for a time, but eventually recover. They are. however, extremely sensitive to sulphur, applied either dry or as a wash, or in connection with other poisons. Soap is also a good remedy. Sulphur. — Flowers of sulphur, mixed with water at the rate of an ounce to a gallon, and sprayed over infested plants, is of great value in the eradication of this pest; or the sulphur may be combined with strong soapsuds. For the application of this spray a force pump with spraying nozzle is a necessity and the current should always be directed to flic lower surface of the leaves. Son/) solutions. — Potash, fish-oil, whale-oil. and other soap dilutions are valuable against the red spider, and the addition of sulphur in- " Trans. St. Louis Acad. s.i.. Vol. V. pp. 540-542. 6 Psyche, Vol. III. i>. .".si. L882. [Cir. KM] creases their effectiveness; bul these washes will injure -nine delicate plants. Moreover, they have no more value as insecticides than neutral soaps of the castile and Ivorj type, or such as are used bj physicians and surgeons. For i lif red spider, as n occurs in greenhouses, particular!} < m pi nut-. such as violets, thai are liable to injury from sulphur, no other rem- edy is employed bj florists generally than frequent syringing or spraj ing with water or with ;i soap solution. Neutral — < »i* j »— are valuable, particularly upon cuttings affected with the red spider, and the bes< results have been obtained in the proportion of a 5 cenl cake to 6 <>r 7 gallons of water. The soap i- shaved with ;i small plane, dissolved in about m gallon of lift water, and then sufficient cold water is added to make the quantity desired. Five gallons arc sufficient for the treat iiu'iit of three or four thousand cuttings of violets. It is customary to allow the soap to remain on the plant- two or three hours and then to syringe thoroughly with clear water, repeating this treatment two or three times, until the "spiders" and their eggs have I n destroyed. Used thus, the soap has little if any deleterious effect upon most plant-. Kerosene-soap emulsion. — An emulsion may l>e prepared by com- bining 2 gallons of kerosene and one-half pound . Lye-sxilphur.—The lye-sulphur remedy was given a thorough "test against the red spider in it- occurrence on beans in Florida, having been applied May 28, 1908, with the result that 98 per cent of the red spiders were killed without in the least affecting the plant- treated. [Or. KM] Pig "•. Elbow attach ment f<>r undi r Bpraj in- Reduced 8 This shows better results than with any of the four insecticides which were tested in that locality by Mr. II. M. Russell," :*> per cent more of the mites being destroyed than by the use of kerosene emul- sion, which slightly injured the plants; 7 per cent more than with the use of sulphur water, and it proved to be much better than lime- sulphur, which was hardly a success as compared with the other-. Lye-sulphur is prepared as follows: .Mix L'o pounds of flowers of sulphur into a paste with cold water; then add 10 pounds of pulverized caustic soda (98 per cent). The dissolving lye will boil and liquefy the sulphur. Water must he added from time to time to pre- vent burning, until n concentrated solution of 20 gallons is obtained. Two gal- lons of this is sufficient for 50 gallons of spray, giving a strength of 2 pounds of sulphur and 1 of lye to 50 gallons of water. An even stronger application can be made without danger to the foliage. This mixture can also bo used in com- bination with other insecticides (Marlatt, Farmers 1 Bulletin 172). Tobacco voter. — Tobacco water is of some use for destroying the red spider, but can not be recommended for violets, ow T ing to it- tendency to weaken the foliage and induce " -pot." Water. — Spraying with water is usually practiced two or three times a week during the growing season, and by a little practice and experiment with a fine-spray nozzle or tip the operator is soon able to ascertain the proper degree of force to use. A pressure of about •_'•"> pounds has proved most effective against this red spider. Care should be exercised to wash off the " spiders " and at the same time to avoid drenching the beds. When it is necessary to spray during winter, work should be done on a bright day, in order that the plant - may dry off in a few hours. Water is also of use on shade trees and shrubs in parks. NOZZLE AND TIP FOB GREENHOUSE USE. Since the general adoption of spraying as a remedy for the red spider, the problem of how to apply a water or other spray so as not to drench the beds has been an important one. To accomplish this object, Dr. B. T. Galloway. Chief of the Bureau of Plant Industry, has devised a small -praying tip which answers the purpose ad- mirably, being particularly serviceable where plant- are syringed or sprayed on a large scale. The following description of the nozzle is taken from Circular 17 of the Division of Vegetable Physiology and Pathology : The spray tip proper is attached to a brass fitting, which in turn screws onto the end of a three-quarter-inch hose. The apparatus is very effective for spray- ing. roses, as it readily serves to keep the leaves in a thoroughly healthy condi- " For particulars see article by II. M. Itussell in Journal of Economic En- tomology, Vol. I, pp. 377-380, 1908. [Ctr. 104] Hon, a ml at tin- aanie time- wets the 1 • • -« i — bill little, li Is also rerj nseful for violets, as with a pressure of 38 i" K) pounds the the plan! can be readily turned over and thoroughly washed without Booking the crowns nnd the bed. in spraying a e plants, particularly violets, it bas been found ad van tageoua to use a lance I s Inches long, made • •( a p le half Incb bi pipe. This Increases the reach, nnd enables the operator m place the wain to better ad van tag plants which under ordinary conditions would !»■ beyi arm's length. The apparatus can be made for 60 cents, and will be found a useful Instrument wherever there Is sufficient water pressure to Insure a proper amount of force. The illustration here presented (fig. li shows the general appear- ance of this i i|> and nozzle. The nozzle consists of a casting turned i<> the desired length and Battened at the end as figured. Through this flattened end ;i narrow -lit is made, which should be absolutely true throughout, so thai the water as it issues will be broken up into streams. It is even sometimes necessary to file t Ik- tips as they come From ili»' Factory, to secure the desired result. iki \i mi \ i ui rancs ikd bbbubs. The methods of control which have been advised above are especially adapted to the treatment of greenhouses infested l>\ the spider. All of the insecticides which have been recommended for indoor use are also applicable to trees and shrubs, the list in- cluding sulphur, which m;i\ be applied in the form of a powder by means of a pow dcr bellows, or mixed with water as previously prescribed, or combined with lye or lime. Soap solutions, kerosene emulsion, and cold water maj be used with profit. Resin wash and lime-sulphur are also used as for the orange mites or red spiders. Of these the lye- sulphur mixture is probably the best, as it is successfully used against these pests in California. The sulphur treatment has an advantage, in that it adheres mure closely to the leave- than other preparation- which have been men- tioned and kills young mites coming in contact with it as -non as they are hatched. Sulphur preparation- are also of value in eradi- cating scale insects which mighl be present at the same time; in fact, when the sulphur i- being applied for scale-insects, red spiders or mites are likewise killed. na \ l mini ni ii;iik \M> GARDEN PI \\ In the treatment of truck crop- infested by the nM spider, little variation from the method- already advised for greenhouse work need be practiced. The same applies to ornamental flowering plants [Cir. 104] li.. 4 Nozxle ;int described. Some of the remedial meas- ures advised for the cotton red spider (Tetranyckus gloveri Bks.), a related species occurring in the (iulf region, may lie followed; in- deed, the same measures are applicable to aphides and other pests which may be present on the plants at the same time. Among cultural methods of control may be mentioned clean garden ing or farming with early fall plowing, keeping down the weeds of the vicinity throughout the year, and destroying crop remnants as early as possible by burning or otherwise. Weeds growing on the edges of fields, in fence corners, and like locations should lie destroyed early in the fall in order that no winter shelter may be left for the pests. Early fall plowing destroys the insects before they have an opportu- nity to leave the old crop plants for weeds and others. During May, 1908, Mr. H. M. Russell, working under the writer's direction at Orlando. Fla., conducted some experiments with reme- dies against the red spider in its occurrence on wax beans. The results obtained, in brief, are as follows: Kerosene-soap emulsion, 1 part stock solution to 10 parts water, killed 95 per cent. Lye-sulphur, 1 pound sulphur, i pound lye, to 4<> gallons water. killed _ 98 per cent. Sulphur water, 1 ounce to 1 gallon water, killed '-'1 percent. Lime-sulphur, 1 pound lime, 1 pound sulphur, to -'> gallons water, killed (is to 85 per cent. The results show that the red spider succumbs to any one of these four insecticides, the probabilities being that kerosene-soap emul- sion, properly prepared and applied, is as satisfactory a remedy as any other applications that could be employed. St MM AH V. The remedies advised may be summarized as follows: For the greenhouse and for general use. sulphur and neutral, whale- oil, and other soap solutions, kerosene-soap emulsion, and spraying with water. For the treatment of trees and shrubs, the same as the above, with the addition of resin wash and the lime-sulphur and lye-sulphur mixtures. For truck a"nd garden plants, lye-sulphur wash and the same remedies as for the greenhouse, with the addition of clean gardening [Cir. 104] MARSTON SCIENCE LIBRARY Date Due i Due Returned Due Returned ;.. m ?i m MAR 2 1995 n t • •**» ■,l MOMENT umvERsmr of florid* 3 1262 05252 3411