MELON LICE 



219 



covered with netting, or the plants very quickly sprayed or dusted, 

 since they are all in a limited area. It may also be necessary to 

 treat the transplanted plants once or twice after they are in the 

 field. 



Melon Lice. — Another insect likely to attack muskmelons, 

 cucumbers and watermelons is the melon louse or aphis (Fig. 130). 

 This insect is likely to be especially bad in hot, dry weather. It 

 commonly appears about the time the plants begin to run. Usually 

 the first attack is confined to a few hills, which may be in various 

 parts of the field. Unless prompt treatment is given, the insects 

 spread rapidly to adjoining hills, and may be distributed through- 

 out the field by the time the first fruits have set. These insects 

 feed upon the under side of the leaves, causing them to curl. They 

 suck the juice from the plant and render the vine so weak that 

 the quality of the fruit is seriously 

 impaired, and in case of a severe 

 attack, especially in dry weather, 

 the vine may be completely killed. 



Under normal conditions, the 

 natural enemies of the aphis, 

 notably the lady beetle, will do 

 much to keep this insect in check. 

 In fact, many growers depend 

 almost entirely upon the work of 

 this predaceous insect to control 

 the lice. If a melon or cucumber 

 hill is discovered to be only slightly infested with lice, and the 

 lady beetles are abundant, it is safe to leave the two species to 

 fight out their battle together. If, however, the lice are abundant 

 on the hills attacked, or the lady beetles are scarce, a common 

 way of preventing the spread of the lice and the possible loss of a 

 large area from the field is to bury the affected hills with dirt 

 where they stand. To be effective this method must be put into 

 operation as soon as the insects appear. 



However, the most efficient method of controlling the lice is 

 spraying the vines with a commercial preparation of nicotine 

 sulfate, known in the trade as '' Black Leaf 40." This is an ex- 

 ceedingly concentrated tobacco product and is diluted with 1000 

 times its volume of water for the spraying of melon lice. Since 

 the Hce are sucking insects, they must be killed by contact, and 

 it is necessary that the spray be so directed as to hit the insects 



Fig. 130.— Melon aphis. 



