GARDEN PESTS IN NEW ZEALAND 



PLUM APHIS (Rliopliwlosiplium nymphcece). This insect is some- 

 times very common during spring upon the shoots and leaves of plum 

 in New Zealand; in other countries it has been found to migrate to and 

 infest the flowers and leaves of water lilies. The insects assume various 

 shades of green, the winged females having the head, thorax, and legs 

 blackish; the "honey-tubes" vary in colour, and may be reddish, blackish 

 or yellowish. 



POPLAR GALL APHIS (Pempliiyux puptdi-im^versus). Fpon the 

 leaf stems of poplar trees in many parts of New Zealand sac-like 

 growths (Fig. 9, 7), measuring anything from half an inch to one inch 

 in length, may be found. These are the galls formed by the Xorth 

 American poplar gall aphis. In each gall are colonies of the aphis sur- 

 rounded by a mass of flocculent secretion. The walls of the gall are 

 thick and tough, with the outer surface wrinkled, while at the end, 

 toward one side, is a slit-like, or sometimes circular, opening surrounded 

 by a thickened rim, presenting much the same appearance as the mouth 

 of a sack gathered together and tied. For the most part, these insects 

 are wingless females only, but during the summer, and particularly 

 toward the end of autumn, winged females develop and migrate to 

 cruciferous plants, such as cabbage, rape, mustard and turnips, or weeds 

 allied to these cultivated forms, upon the roots of which they establish 

 colonies surrounded by a woolly secretion. In spring a return migration 

 to the poplar takes place, and galls are again established. 



Leaf-hoppers. 



Leaf-hoppers form a group of small, narrow-bodied, sap-sucking 

 insects; as the name implies, they infest the foliage of a variety of 

 plants, and when disturbed have the habit of suddenly leaping or 

 hopping to safety; the species present in Xew Zealand are usually of a 

 greenish or yellowish colour. The adult insect is winged (Fig. 8, K, L), 

 and the female lays her eggs in the plant tissues (H) ; from these eggs 

 the young wingless hoppers (I) hatch and attack the plant; as they 

 grow, wings develop (J), but until then the insect depends for loco- 

 motion upon its hopping powers. 



The most outstanding species in Xew Zealand is the apple leaf- 

 hopper (Typhlocyba austmlis). This insect causes considerable damage 

 to apple trees unless controlled, which can lie effected by spraying with 

 nicotine-sulphate against the young insects in the spring. 



White-flies. 



White-flies, or mealy-wings, are minute sap-sucking insects, 

 having the body and wings covered w r ith mealy wax. The female 

 (Fig. 8, P) lays her eggs, frequently in circular batches, upon foliage, 

 and the young insects (X) are active, but settle down and commence 

 feeding soon after hatching. Later the insects change to another form 

 (0), without legs and antennas, and so resemble scale insects to a certain 

 extent ; from the latter, however, they may be distinguished by the waxy 

 covering, bearing spine-like processes, and by being surrounded by a 

 distinct marginal area. An important species in Xew Zealand is the 

 greenhouse white-fly (Trialeurodes vapomriorum ) , against which fumi- 

 gation with calcium cyanide is the best as a check. 



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