Misra, C.S., 1913.
The red spider mite on jute (Tetranychus bioculatus Wodd-Mason). The Agricultural Journal of India, 8 (4): 309-316.
Abstract
The discoloration of the jute leaves frequently observed in the-fields and in experimental plots is due to a phytophagous mite called the Bed Spider, or Spinning Mite (Tetranychus bioculatus [Oligonychus coffeae]). It repeatedly punctures the leaves of the plant, sucking some of the sap; more damage is done by the sap which runs to waste than by the loss of that which the mite actually uses for food. The waste sap decomposes and forms a stoppage in the sap channels which nourish the rest of the leaf. The infested leaves turn a deep coppery green colour, curling over and becoming very crisp. This Red Spider is also found on cotton, castor, mulberry, orange, indigo, Triumfetta neglecta, Urena lobata, Hibiscus ficulneus, H. penduriformis, and H. abelmoscus. It has been under observation since 1909, when it was noticed on the jute for the first time. In May-June 1910, it attacked castor. Last year the spider was found to hibernate in the adult stage on the lower surface of castor leaves. The adults remain inactive until February, after which they copulate and lay eggs. They increase extremely during April, May and June. The adults lay eggs the day after reaching maturity. Each female lays from 80-90 eggs, the larva emerging within 4-5 days after the eggs are laid. On hatching, the larva begins to feed, and spins a web all round itself. A few days later it undergoes metamorphosis and emerges as an adult, the whole life-history occupying only 8-9 days. Starting from a fertilized female on the 1st March, there will be 3, 500, 000 spiders ready to reproduce at the end of the month, provided the weather conditions are suitable. Thus it is evident that if measures are to be taken to combat the pest, they should be taken early to prevent this enormous increase. There are five known parasites upon the mite: a small ladybird beetle (Clanis soror, Ws.), a small black Staphylinid beetle, a small Coccinellid or Corylophid beetle, a species of Scymnus, and Brumus suturalis[Brumoides suturalis], F.
Rain is fatal to the Red Spider; a shower has frequently been observed to wash away and kill numbers of them from infested trees. From this it follows that plants sprayed with sufficient cold water would be freed from the pest. In nurseries and with plants in. pots, much good is done by fumigating the affected parts with burning sulphur. But this is impossible in the open, and in this case a good remedy is either dusting the plants with flowers of sulphur, or spraying them with a mixture of flowers of sulphur and crude oil emulsion. Roll sulphur, no matter how finely powdered, must not be used, as it invariably clogs the nozzles of the spraying machine. The following formula is given: -crude oil emulsion, 1/2 pint; flowers of sulphur, 2 ozs. ; water, 4 gals. The sulphur should be thoroughly mixed with the emulsion. High pressure sprays should, if possible, be used, in order to penetrate the webs inside which the nymphs are protected. If there still remain mites after the first spraying, the process should be repeated with twice the quantity of sulphur. The paper concludes with a table giving the size of the plot treated, the formula for the spray, the machine used, the time taken, and the labour and cost. Five plots of 1/30 acre each were sprayed with liquid prepared as given above, with a Gould's Standard Spray Pump, mounted on a cart. The time taken was two hours, and the total cost for four men and material for spray liquid was 2s. 6d.
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