The Plant Louse Observations And Field Studies
Plant some melon, radish or other seeds in fertile soil in pots for use in this study. When lice appear on crops in the garden or field, collect a leaf with a few on it and carefully transfer them to the leaves on your potted plants. Watch the lice feed and increase from day to day. A reading lens or a magnifying glass will be helpful as plant-lice are very small. How do they move about? Can you count their legs? How many have they? Can you see their eyes and feelers? When feeding observe how the beak is pressed against the leaf. Disturb one while it is feeding and see it attempt to loosen its mouth parts.
Common apple aphis showing a winged and wingless agamic summer forms at a and c, one with wing pads formed at b, and a recently born young at d. (After U. S. Dept. Agri.)
In the garden examine and see if you can find lady-beetles or other parasites attacking the lice. Collect some of the enemies of the lice for your collection. Make a gallon of tobacco tea by soaking one pound of tobacco stems or waste tobacco in one gallon of water for a day or use one ounce of forty per cent nicotine sulphate in three gallons of soap suds and spray or sprinkle infested bushes or vegetables with it. In an hour examine and see what effect it has had on the plant-lice. Nicotine is the most effective chemical for killing plant-lice. Do any of the lice develop wings? If so, how many? Wings develop on some of the lice at times when a plant or crop becomes too heavily infested by them. This enables some of the lice to spread to new food plants before old plants are completely destroyed and the colony of lice starved.
Wooly apple aphis, showing how they cluster in masses on limbs and secrete the white, wooly protection over their bodies.
Make a careful enlarged drawing of a winged plant-louse and a wingless one showing legs, feelers, beak, honey dew tubes on back and body segmentation. If ants are seen to attend the lice observe them carefully and describe their work. The ants feed on a sweet honey dew excretion discharged by the lice.
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