GENERAL PRACTICE* ENEMIES 



253 



Essential methods to prevent attacks by insects must depend on their mode of life. 

 No means surpass the destruction of the mature insect before laying its eggs, and no 

 natural agents effect this so satisfactorily as do birds, whilst certain parasitic insects 

 reduce the numbers of the pests. These will be referred to ; yet, though useful, the 

 fruit grower must not trust to natural agencies, but take prompt steps to prevent 

 infestation, and destroy parasites inimical to fruit crops. Means to suit special cases 

 may be needed, yet some are applicable for the destruction of several kinds. 



American Blight or Woolly Aphis (Schizoneura (Eriosoma) lanigera). The woolly 

 aphis is an almost universal pest of the apple. It first appeared in England in 1787, and 

 on the supposition that it was introduced from America received the opprobrious title 

 American Blight. Though common in gardens and plentiful in orchards, infections are 

 somewhat local, due to first introduc- 

 tions escaping observation, or re- 

 pressive steps not being taken until 

 the pest gets thoroughly established 

 and the trees well-nigh ruined. 



The aphides (so called) possess 

 six legs, a head with two horns 

 (antennae), and a sucking tube (ros- 

 trum). The males have two pairs 



of transparent wings, and appear in 

 July and August. The egg-producing 

 female also has wings, and its colour 



. . Fig. 73. WOOLLY APHIS (SCHIZONBTJRA LANIGEBA). 



is yellow, tinged with red. In their 



References : Upper figure winged female ; lower lelt-hand 



early Condition the aphides are pink- figure wingless female ; lower right-hand figure viviparous 

 i -i /r . , , .., female and young in wool. 



ish brown (becoming darker with 



age) and slightly clothed in down ; but when adult the insects exude cottony threads 



from their pores. 



These lice differ from the true aphides in the honey-tubes (cornicles) being 

 absent, therefore not secreting "honey dew," but the wool exuded sufficiently indi- 

 cates their presence, whilst sheltering the young from rain and cold. In these 

 masses of white woolly matter the wingless larvee pass the winter, no frost appearing 

 to injuriously affect them. 



The woolly aphis aptly resorts to places where branches and shoots have been 



