34 MASSACHUSETTS HORTICULTURAL SOCIETY. 



grown in ten or twelve days, and as all are females and at once 

 commence gi^'ing birth to more young — no males occurring during 

 the summer — it is e^ddent that the aphid population will increase 

 at a geometrical ratio of over 100 every ten days. Astonishing 

 computations have been made as to what would happen were there 

 no natural checks for such prolific reproduction and it has been 

 shown that if all the descendants of a single aphis were to live and 

 reproduce during a summer season, and the resulting progeny were 

 placed side by side, they would form a line from the earth to the 

 farthest star visible vnth the strongest telescope. This is of course 

 mere hypothesis for their natural enemies always hold them in 

 check, but the mathematically inclined may verify the computation. 

 Thus we can readily see that though our indi%'idual aphis can do 

 but little harm, if it be allowed to reproduce for but a few genera- 

 tions, its progeny may be numerous enough to destroy a crop. 

 This has been frequently observed with the pea aphis. Fields 

 where indi^adual aphides could only be found after long search 

 have been utterly destroyed by their progeny within six weeks. 

 Injury is worst in dry seasons as the aphides are usually kept under 

 control by a fimgous disease which propagates only with normal 

 moisture. To detect the first appearance of this pest and to rid 

 the vines of it early in the season is therefore of the greatest impor- 

 tance, as indeed in fighting all aphides. Kerosene emulsion diluted 

 so as to contain 10% of kerosene, or whale oil soap one pound to 

 six gallons of water, will be found effective for spraying the aphides. 

 The latter is more readily mixed and can be secured of any seedsman 

 or insecticide dealer. It should be remembered that the aphides 

 are sucking insects, drawing their food from the interior of the leaf, 

 and that these insecticides kill them by contact, so that a mere cover- 

 ing of the foliage is of no value. The aphides must be hit to kill 

 them, and this will require a spray with some force and applied 

 from beneath the vines so as to reach the under sides and get into 

 the terminals. Early maturing varieties, such as Alaska, are much 

 less attacked and indeed are often quite free where later sorts are 

 practically destroyed. 



Every garden has a few heads of cabbage and in many localities 

 the crop is grown extensively. The common cabbage worm is 

 among the best known of all our garden insects, both as a larva and 



