d70 state board of agriculture. 



place between the base or petiole of the leaf and the twig. Here they 

 grow, and in the course of about a month change to the winged or adult 

 form (Fig. 4). In this stage the insects have strong jumping legs and 

 powerful wings, which enable them to escape when approached or 

 when an attempt is made to spray them*. Several broods are raised 

 during the season, and the insect passes the winter either as an adult or 

 immature. 



While the pear psylla may be present for some time without a serious 

 outbreak, it is certain to multiply to an enormous extent when all the 

 •conditions are favorable, and usually when least expected. 



EEMEDIES. 



Most of the injury is done before the middle of June, and as the in- 

 sects are destroyed most easily when in the immature stage, two or 

 more thorough sprayings with kerosene-emulsion during the last week 

 of May and the first week of June will so reduce the pests that very little 

 injury is to be feared for the rest of the season. The emulsion should 

 be made according to directions given in the chapter on insecticides, and 

 should be diluted with fifteen times its volume of water. A winter 

 wash of whale-oil soap undoubtedly would kill great numbers of the 

 insects, which always pass the winter on the twigs and branches or in 

 crevices of the bark. 



Spraying at any time after the eggs hatch will prove beneficial, but 

 experiments have shown that the best results may be obtained at the 

 times indicated. 



PLANT LICE OR APHIDS. 



If there is any group of insects that requires the constant attention 

 of nurserymen, green-house owners, orchardists and farmers, it is the 

 family of plant-lice or aphids. The season of 1897 has been unusually 

 favorable for these vermin, as is always the case when the spring opens 

 -moist and cloudy, with very little hot weather early in the season. Such 

 widespread and well-known pests require verv little description; their 

 small, pear-shaped bodies, rarely exceeding one-quarter of an inch in size, 

 with the slender legs and feelers, are known to everyone. The life-his- 

 tories of these plant-lice are, however, not so well known, and in many 

 •cases they are as yet a mystery. Many species pass the winter in the egg 

 stage, although a large number of species are not yet known to produce 

 eggs. The "winter eggs." hatching in the spring, produce wingless 

 females, which bring forth living young without the intervention of the 

 male. In some cases these young produce in turn winged females, in other 

 cases wingless females (but these, whether winged or wingless, have the 

 same power of producing young without pairing), and in the great major- 

 ity of cases, if not in all, this method of reproduction is carried on until 

 fall. Then in some cases males and females are produced, which, after 

 pairing, give rise to one or more eggs, which serve to keep the species over 

 winter. In many instances, as with the black peach-aphis and the 

 grain-aphis, the aphids themselves live over winter. In some cases, as in 

 'the case of the hop-aphis (Aphis humuli), the winter eggs are laid on 



