THE GREEN SPOT 



Like Bumps on a Log 



Scale insects can give woody or 

 namentals owners and interior- 

 scapers a real headache. Not only 

 are they difficult to control, but 

 they can be difficult to diagnose as 

 well. 



Scale insects cover a large group- 

 ing from the order Hemiptera and 

 sub-order Homoptera (just like 

 aphids and whiteflies). The scale 

 sub-order is divided into three fami- 

 lies: coccidae, diaspididae, and pseu- 

 dococcidae, commonly known as soft- 

 scales, armored scales, and mealy- 

 bugs, respectively. 



Soft scales, in general, are large — 

 up to an eighth of an inch. The fe- 

 males are covered — in their adult 

 stage — with a hard body covering 

 (which leads many people to believe 

 these are armored scales). They can 

 produce honeydew, a sticky, sugary 

 excrement which may attract ants. 

 Ant will harvest the honeydew and 

 provide some protection to the scales 

 from their natural enemies. Although 

 the adult males are winged, they are 

 rarely seen. The females, on the 

 other hand, are seen as "bumps" 

 which often resemble bark features 

 in color and shape. The immature 

 "crawler" stage is often hidden by 

 the female's cover, but they are usu- 



ally more mobile as they seek out 

 their final feeding spot. 



Armored scales are, in general, 

 very small (down to .2mm). They, 

 like their soft cousins, have a tough 

 cover. The males are winged and 

 rarely seen; the crawlers are similar 

 as well — just a lot smaller. One big 

 difference is that armored scales pro- 

 duce no honeydew. This makes 

 them even more difficult to detect. 



Mealybugs lack the hard covering, 

 but the males are winged and rarely 

 seen and the crawlers are similar to 

 those of the soft scales. They also 

 produce a lot of honeydew and at- 

 tract ants, but, for most people, they 

 are not considered a scale insect. 

 Mealybugs have waxy coats which, 

 like their cousins' hard coverings, 

 provide protection. Like many other 

 scales, the eggs of many mealybug 

 species are protected, often inside a 

 waxy, cottony substance. Some mea- 

 lybugs give birth to live young, like 

 aphids. 



Control can be difficult. Chemi- 

 cals must be formulated to penetrate 

 the protective coverings. Some scales 

 have toxins in their saliva that can 

 cause leave to curl protectively 

 around them. Parasitic biological 

 controls can be difficult to use be- 



cause many are species-specific (you 

 must know exactly what you're deal- 

 ing with). Horticultural oils can be 

 used successfully if applied thor- 

 oughly enough to coat and smother 

 the insects. Use cautiously, as horti- 

 cultural oils — especially when ap- 

 plied heavily — can cause phytotox- 

 icity in some plants. 



So what's the best cure? Detect 

 scales early by scouting properly; 

 hand-apply oils and such; locate the 

 more susceptible crawlers and use 

 soap and other physical products on 

 them; use predatory biological con- 

 trols which care less about species 

 and are more opportunistic; keep 

 your plants clean and healthy, put- 

 ting them outside whenever possible 

 to let Mother Nature take care of 

 her own. Some systemic chemicals 

 can (according to the manufacturers) 

 provide some level of control, but 

 are typically very harsh. Perhaps it 

 might be better to simply discard 

 the affected plant material and try 

 again with fresh stock — although 

 this can be a costly option. Some- 

 times, however, it can be your least 

 expensive fix. 



Mike Cherim, president of the 

 Green Spot, Ltd., can he reached at 

 6oj-p42-8p2$. 



