11 



Plant Lice. 



Practically all vegetables are subject to attack by various 

 species of plant lice which are also known as "aphids," "aphis" 

 and "green fly." On account of their small size, plant lice 

 are to a great extent unnoticed, but when conditions are 

 favorable to their increase they are capable of seriously damag- 

 ing plants on which they feed. These small, soft-bodied 

 insects occur as winged and wingless forms, and feed by means 

 of a jointed beak with which they pierce plant tissues and suck 

 the sap. The species which feed upon vegetable crops live 

 for the most part on the under surface of leaves. Plant lice 

 reproduce so rapidly under favorable conditions that they are 

 capable of seriously weakening and even killing their host 

 plants in a short time unless checked by natural enemies or by 

 the application of control measures. 



Control. — Since plant lice do not feed on the exposed portion 

 of the leaf, stomach poisons, like arsenate of lead, are useless. 

 Therefore a contact insecticide is necessary. Nicotine sulphate 

 sprays (see page 6) will readily kill these soft-bodied Insects. 

 It should be remembered that this is a contact insecticide and 

 kills only the insects actually touched. It is therefore neces- 

 sary to be very thorough in spraying for the control of plant 

 lice. Spraying should be done promptly, as soon as these 

 pests appear and before they have curled and seriously injured 

 the leaves. Soap preparations (see page 6) are also of value 

 in controlling plant lice in small gardens. 



Onion Thrips. 

 The small yellowish "thrips," which chafe the epidermis from 

 green leaves and suck the juices, causing the plants to dry out, 

 whiten and die, have become well known to onion growers. 

 The adult thrips is about one-twenty-fifth of an inch long, of a 

 pale yellow color, with a blackish tinge. The slender, elongate 

 body bears two pairs of narrow, bristle-like wings, which are of 

 no value for flight. This species attacks a large number of 

 vegetables, including onions, cabbages, cauliflowers, cucumbers, 

 squashes, pumpkins, tomatoes, turnips, etc., as well as numerous 

 other plants and weeds. It often severely injures onions, to a 



