1950 



ENCYCLOPEDIA OF PRACTICAL HORTICULTURE 



promotes early ripening and better fruit. 

 On a small patch only is this a practical 

 measure. If applied, the covering need 

 remain only until the first berries begin 

 to color, because by that time the plants 

 would be no longer attractive to the 

 beetles. 



A much better prospect for avoiding in- 

 jury lies in the selection of varieties. Pis- 

 tillate varieties are not subject to attaclc 

 by the beetle, and it should be possible 

 to secure a good pistillate variety to form 

 the main bulk of the crop. This will 

 need, as a pollenizer, a profusely flower- 

 ing staminate variety, which may form 

 every fifth row in the field, and the crop 

 from which may be sacrificed to the 

 beetles if they furnish flowers enough to 

 pollenize the others. 



Clean culture is highly important, and 

 especially wild blackberry and raspberry 

 in the vicinity of strawberry patches 

 should be destroyed. Burn all rubbish 

 and undergrowth around the edges of the 

 fields when the ground is frozen in 

 winter. Especially burn along and under 

 fences and at the edges of woods, where 

 the bulk of the wintering beetles are usu- 

 ally found. 



During their long dormant stage, from 

 mid-July to the following April, the in- 

 sects are exposed to the attacks of small 

 rodents, predatory insects, toads, frogs 

 and lizards. It has been demonstrated 

 in the case of the cotton boll weevil that 

 few survive the winter unless shelter con- 

 ditions are favorable. 



Strawberry White Fly 



Aleurodes pacTcardi Morrill. 



These white flies are very small, four- 

 winged creatures, which, when at rest on 

 the underside of the leaf, look like min- 

 iature moths. This impression is height- 

 ened by the white mealy powdering that 

 covers the surface of the insect, and is 

 responsible for one of its common names. 



These flies occur at intervals through- 

 out the summer from May to September, 

 and lay their small, shortly stalked eggs 

 on the undersides of the leaves. They 

 hatch in about ten days into active yel- 

 lowish larvae that very much resemble 



those of scale insects. As in the case of 

 scales, this active stage is short, and in a 

 short time the little creatures settle down 

 and begin to sUck the plant juices. 



Then their resemblance to the scale in- 

 sects becomes yet more marked for a 

 time; they lose antennae and legs and are 

 as much fixed to the plants as any scales. 

 As they grow, this outside case or scale 

 becomes fringed with waxy filaments, and 

 honey-dew is excreted. When the insects 

 are abundant this honey-dew dropping to 

 leaves below may form a sticky varnished 

 surface, upon which a black soot fungus 

 develops. 



As a result the foliage loses vitality and 

 dries up or decays, seriously injuring or 

 destroying the plants, especially if they 

 be young or small. 



The insects are rarely abundant enough 

 to do severe injury on large plots, and it 

 is only in droughty periods that they 

 seem to become dangerous. 



Eemedyial Measures 



In the active larval stage this white fly 

 succumbs readily to any of the contact 

 insecticides at moderate strength, and the 

 adult is not much more resistant, though 

 this is harder to reach, because it flies 

 readily if not very strongly. As against 

 the nymphs or scale-like stages, kerosene 

 emulsion diluted with 12 parts of water 

 seems to be most effective; but it must 

 be applied with a bent nozzle so as to 

 hit the underside of the foliage. If 

 adults are flying when the application is 

 made, a fine spray is desirable, for this, 

 if applied with sufficient force, will fill 

 the air above and around the plants with 

 a fine mist that will hit and disable many 

 of the insects on the wing. Whale-oil 

 soap suds, one pound in six gallons of 

 water, has also been used with good 

 effect in the same way. 



A badly infested patch should never be 

 used as a source for plants to make a new 

 bed, unless these plants are first fumi- 

 gated with hydrocyanic acid gas. 



J. B. Smith, 



New Jersey Experiment Station Bulletin 225. 



