41. He specialized in studying the armoured scale insects . 42. Isopropyl alcohol ( rubbing alcohol ) is effective as a topical insecticide, particularly on scale insects . 43. Susceptible to scale insects and red spider mites. 44. Scale insects , tiny bugs that feed on the sap of trees, are another favorite ladybug meal.45. Mortality of scale insects ( caused by natural enemies ) can be double with insectary plantings. 46. The red pigment carmine is produced from powdered bodies of scale insects , so some vegans avoid it. 47. Some types of scale insect are economically valuable for the substances they can yield under proper husbandry. 48. The ministry said the pests appeared to be either aphids or scale insects , not the pink mealybug. 49. In order to obtain all the nutrients they need, the scale insects ingest large quantities of sap. 50. Beech bark disease is a fungal infection that attacks the American beech through damage caused by scale insects .
