University of Massachusetts Amherst ScholarWorks@UMass Amherst Masters Theses 1911 - February 2014 1955 The Biology of the soft brown scale, Coccus hesperidum Linn. and its control in the greenhouse. Donald Lewis McLean University of Massachusetts Amherst Follow this and additional works at: https://scholarworks.umass.edu/theses McLean, Donald Lewis, "The Biology of the soft brown scale, Coccus hesperidum Linn. and its control in the greenhouse." (1955). Masters Theses 1911 - February 2014. 2903. Retrieved from https://scholarworks.umass.edu/theses/2903 This thesis is brought to you for free and open access by ScholarWorks@UMass Amherst. It has been accepted for inclusion in Masters Theses 1911 - February 2014 by an authorized administrator of ScholarWorks@UMass Amherst. For more information, please contact [email protected]. '!)!)' BfOEOOY Of THE SOFT BROWN SCALE COCCUS HESEISklUUM ESNIY AND DD CONTROL IN '1 HD GKEi-NIK.>U.SE DA N 9 bb m biology of the soft mom some, coccus msmawu im<. and its co tmoi m the wmmxm Donald U McLean *• Thesis submitted in partial fulfillment for the degree of Master of Science University of Massachusetts Amherst May$ 1^5 * DEDICATION 1 wish to dedicate this thesis to By wife, Joanne H* McLean, whose unlimited encouragement and perseverence made this work possible* TABLE OP COSTEKPS Pago INTRODUCTION..... 1 Importance of the Soft Brown Scale In the Green¬ house ............. 1 Discussion of the Fungus 1 Discussion of the SuperfaadLly Coocoidea or Scale Insects .. 2 Distribution of the Soft Brown Scale....•••• ? Importance of Soft Brown Scale on Citrus .. 7 Host Plants *•..»»...9 Discussion of the Taxonomy.*.• 10 PROCOT. 15 Procurement of Plants and Insects ... 15 Infestation of the Plants for life History Studies 15 Infestation of the Plants for Some Insecticidal Studies .. 19 Confining the Crawlers to a Small Portion of the Leaf. 19 Recording the Temperatures ....................... 22 BIOLOGY OF THE SOFT BROWN SCALE.27 Preparation for Study of the Biology 27 The Active Nymph .. 26 !£S® Development of the First Instar.• 33 Development of the Second Instar •••••••«••••••. 36 The Adult Female Scale •............. 39 Sex Ratio of the Soft Brown Scale .. 1*2 Reproduction...*.. 1*2 Number of Qenerations «..... 1*1* Summary and Conclusions of the Life Cycle of the Soft Brown Scale..... 1*1* CONTROL OF THE SOFT BROWN SCALE IN GREENHOUSES ... 1*8 Purpose of the Insecticide Tests .... 1*9 Insecticides Used in Controlling the Scales .... 50 Phytotoxicity Tests... 5l Procedure of Testing the Insecticides.. 53 Mortality on Untreated or Check Plants. 55 Summary of the Mortality of Scales on Untreated Plants ....... 56 Treatment with 57 Percent Malathion Eraulsifiable Concentrate .. 57 Treatment with 25 Percent Malathion Wettable Powder .. 58 Treatment with 50 Percent DDT Wettable Powder •• 59 Tests with 23*5 Percent Aldrex, 15*8 Percent Dieldrex, and 19*5 Percent Endrin Emulsifi- able Concentrates .. 60 Summary of the Tests with Aldrex, Dieldrex, and Endrin ......*• •.• 60 Page Control with 9$ Percent Sulfatep ... 61 StusBaary of the Teste with Sulfatep .... 63 General Suacary of the Insecticide Tests.. 63 BIOLOGICAL COKTBOL OF THE SOFT BBC$H SCALE.. 77 CONCLUSIONS.. 85 LIST OF RSFSnBHCE8 ... 87 tiCmmxMmmns The writer is deeply indebted to Drs. Frank R* Shaw and Waiter Banfield and Professor Harold White who, because of their constant Interest, assistance and helpful criticism, made this work possible* Appreciation is also expressed to Mr* Clarence Mitchell and Mr* Edward Boch of Butler and 10man Greenhouses in Hadley, Massachusetts for their very generous cooperation in the procurement of plants and specimens* IWTHODUCTIQH Importance of the Soft Brown Scale In the Greenhouse The Soft Brown Scale, Coccus hesperlduro Linn* is on© of the most important Insect enemies of many greenhouse flowering plants* It is a serious pest of gardenias and camellias* As far as gardenias and camellias are concerned, the scale attacks the flower buds, the leaves, and the stems* The insect forces its beak Into the plant tissues in order to suck the Juices and thus reduces the overall vigor of the plant* If the bud is attacked, it takes on a dark brown color, later turning black and eventually drops from the plant* The attacked leaves may show a yellow chlorotic effect If the infestation is great, but of greater im¬ portance, a black sooty mold grows on the honeydew excreted by the scales* In the preparation of gardenia corsages, five perfect green leaves are required to make a backing* The presence of honey dew and other foreign materials nrevents the use of such leaves* The mold and honeydew are difficult to remove by any method that would not damage the leaves* In a severe infestation, the lack of suitable leaves for the backing may be more important than any other damage* The necessity of utilising sore man hours for the washing process is of great economic concern to the green¬ house operator* Discussion of the Fungus The fungus belongs to the group known as Fyrenoaycetes and 2 has been described as belonging to Meliola species* It grows wry rapidly on the sweet, sticky honeydew excreted by to® scales* According to Wlgglesworto (1939), honeydew is composed of 16*7 percent sucrose, 2li*$ percent invert sugar, 39*U percent dextrin, and 3*0 percent protein* As is signified by its name, sooty mold, the fungus has the appearance of a black soot spread over toe leaf* (See Fig* 1*) If clothing comes in contact with the fungus covered leaves, a black smudge is left on the clothing which is difficult to remove* The hypha© of the fungus are black and thus give the "sooty* appearance to toe leaves* Quayle (1911) stated that it will not develop without the presence of honeydew and is saprophytic developing on the honeydew* Not only is the appearance of the fungus detrimental, but it is thought also to interfere with the normal physiological function of the leaf, as transpiration, respiration, and photosynthesis* The fungus is associated with nsany scale insects, but also with other insects such as Aleyrodldae, or white Hies; Aphididae* or aphids; and Payllidae, or peyllids, all of which excrete large amounts of honeydew* Discussion of the Superfainlly Coccoidea or Scale Insects The scale insect group is placed under the order Hemlptera^ suborder Homoptera* and the Superfamily Cooeoidea* Essig (l?h2) gave a good description of all toe groups of scale insects* The suborder Homoptera comprises a large number of highly specialised • * ■r. f*r • k \>r%a ) ' ^ ds . «V ■ " .j? ■* ■ ■ ■ *-'V: f •;y. , i;« j ■ > m -If ■ Jww Fig. X. Sooty oold and honoydow on a gardenia leaf. -fc- and diversified families difficult to characterise an a group* Iho members are wingless or winged* soft and delicate or hard and elastic* naked, hairy, or covered with wax in various force* dull or brightly colored* sexual or parthenogenic* oviparous or vivipar¬ ous* and varying in sis© from 0*3 ma* to 80 am* Practically all forms are phytophagous and mostly injurious to agriculture, but cer¬ tain species have played an ia^jortant part in the production of dyes, waxes, lac and honeydew* The super family Coccoldea* which includes the scale insects and mealybugs, contain the most highly specialised of all BeadLptera and the most heterogenous of all Insects* The bodies that are naked arc usually ohltinlsed exteriorly while the large majority of species, which are protected by wax, secreted in a great variety of consisten¬ cies, or are covered by a tough scale or shell, have, as a rule, a soft and delicate exoskeleton* The male has well-defined body regions, but the female appears as a poorly organised mass of Inert living material* Although the members of many families are able to move metre or less freely though slowly throughout life, others, when mature, are capable of very little or no movement* Whan first born, however, all are active and energetic* These wanderers keep on the move and can travel long distances in search of food over a period of several days* But after the first molt certain species shed with the skin their an¬ tennae, legs, and anal spines so characteristic of young cooclds and $ become fixed for life, protected beneath and above by a waxy- chitlnous shell and supplied with the juices extracted from the plant to which they are attached* The family Pseudocoocldae which contains the mealybugs Is probably the most primitive under the superfamily Coccoidea* It is a large family of destructive coccids, the members of which are elongate-oval, soft, with distinct segmentation, and usually covered with mealy or cottony wax secretion which may protrude as short lateral anal filaments* The females are further characterized by having well- developed legs | antennae absent, reduced, or nine-segmented* The eggs are frequently laid In loose masses of cottony wax or felt-like ovi¬ sacs* Some forms are viviparous* The males are delicate, wingless or winged Insects with two long caudal wax filaments* Mealybugs occur on the tops and on the roots of the host plants and are often sufficiently abundant to do great damage to cul¬ tivated and ornamental plantings* They occur throughout the world and are counted among the most destructive pests* Tte family Coccldae* which la often erroneously referred to as Lecanidaej contains the Soft Scales and the Tortoise Scales* The Soft Brown Scale, Coccus hesperidtaa* is a member of this family* This large family is composed of a number of variable genera and is one of considerable economic importance* The members are more or less active throughout all stages, except some that are fixed in the last 6 stage o Hie adult resales are elongate-oval and flattened or nearly hemispherical or globular in form} with leathery or hard exoskele- ton which is smooth, roughened, naked or «ll$itly covered with waxj ■ V;A brown, black, or mottled in col or o The eggs, or the young In vivi¬ parous species are deposited beneath the body.