Pulvinaria floccifera (cottony camellia scale)
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Pulvinaria floccifera Family: Coccidae (PUHL-vuh-nair-ee-ah flah-SIH-fair-ah) Common name: cottony camellia scale; cottony taxus scale; cottony yew scale; cushion scale Host plant: Camellia, Ilex (holly), Pittosporum (cheesewood), Euonymus (spindle tree), Hedera helix (English holly), Taxus (yew), Hydrangea, Rhododendron |
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Adult size: Females are flat and oval-shaped; one-eighth of an inch in diameter. Males in 2nd instar stage are smaller. Adult winged males are tiny; difficult to see in flight.
Life Cycle: one generations per year
Description: Adult females are oval-shaped and tan in colour with dark brown edges. They lay their eggs, in late spring, in clusters of up to 1000, inside fluffy cotton-like ovisacs which are roughly a quarter of an inch (6.5 mm) long. Yellowish-brown crawlers emerge in June or July, here in the Pacific Northwest. Hatching crawlers either crawl or are carried by the wind to a suitable leaf where they crawl to the underside, inserting their mouthpart into or beside a vein to suck up the sap. Second instar, immature female crawlers over-winter on the leaves, if the plant is an evergreen, or on the twigs if it is deciduous. They emerge in spring when temperatures reach 10 °C (51 °F). It is unclear whether there is a third instar stage but if there is one for this scale species, only the females undergo this stage and it only lasts for 2 – 4 days. The smaller males go through a pupal stage where they develop wings, emerging in late summer to search for females. The males mate with immature females and die in 1 – 2 days. There is one generation per year.
Special Notes: Male and female sexuality cannot be determined until crawlers reach 2nd instar stage. Females can reproduce both sexually and parthenologically.
Remedial Actions: As this is a soft scale insect…one with a soft body…they are treatable with horticultural oil. (The oil coats the soft-bodied insect and smothers it.) Spray the infected shrub in late winter when temperatures are above freezing and there is a rain-free period of 24 – 48 hours. Be sure to coat both the upper and lower sides of the leaves. This will catch the pregnant females before they have a chance to lay their eggs. If your timing is off, spray the plant in late June or early July to catch the emerging crawlers. However, do not spray at this time if temperatures are forecasted to reach 35 °C (95 °F). Plants may be stressed and the oil may have an adverse effect on the plant.
In our Zone 7a garden: Sometime around 2010 or 2011, we noticed our 45 year old camellia had a few cottony things on the underside of some of the leaves. There was also some sooty mould on a few leaf tops but as the shrub did not appear to be stressed, we did not worry about it. However, in late fall of 2014 we noticed there was a lot of black sooty mould on most of the camellia shrub. That was when I went searching for answers and had the pest identified as cottony camellia scale, Pulvinaria floccifera. John sprayed the whole shrub with horticultural oil in February 2015, making an effort to get the undersides of the leaves as best he could. And it paid off. I did periodic searches throughout April, May, June, and July of 2015…only finding a very few old cottony ovisacs and no scales. What a relief. But…doing a check on a few leaves in January 2017 and I have found a few cotton ovisacs and some over-wintering females. The camellia has been put on the list for a dousing of horticultural oil next month.
Posted on January 25, 2017 |
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Hyphantria cunea (fall webworm)
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Hyphantria cunea Common name: fall webworm Family: Arctiidae Order: Lepidoptera Host plants: wide range of about 90 species, including: fruit trees, walnut, maple, willow, alder, arbutus, cottonwood, and sweetgum. Adult size: wingspan: 1.4 – 1.7 in (35 – 42 mm) |
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Life cycle: Generations per year: one, in the Pacific Northwest
Northern race, (sometimes called orange race or black-headed race), adults start emerging in mid- to late May after over-wintering in the pupal stage. Like most moths, the fall webworm is nocturnal and attracted to lights. Females lay 400 – 1000 eggs in a single layer on the underside of a leaf on her chosen host plant. They are iridescent green in colour and lightly covered with scales from the female’s abdomen.
Reaching full size in four to six weeks, the mature larvae drop to the ground to pupate in leaf litter, or in the soil, where they will over-winter. They will also pupate in crevices in the bark of the tree. The pupa is dark brown in colour and about five eighths of an inch long. There is generally just one generation per year in the northern race.
Special notes: Most years the numbers of fall webworms are not too severe, so they rarely do any serious damage to the trees…except for their unsightly webs and the defoliation of the leaves. However, as with most insects, the fall webworm numbers can increase to drastic proportions for one or two years running before returning to more moderate numbers once again. During these heavier infestations, there will also generally be an increase in predatory insects and birds who do a good job of going after this pest. Gardeners can assist in controlling this pest by cutting out the webs and bagging for the garbage.
Updated on October 17, 2018
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Helicoverpa zea (tomato fruitworm)
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Helicoverpa zea Common name: tomato fruitworm; corn earworm; cotton bollworm Family: Lepidoptera Host plants: tomato, corn, cucumber, eggplant, pepper, potato, sweet potato, snap bean, lima bean, pea, lettuce, spinach, collards, artichoke, asparagus, cabbage, pumpkin, squash, watermelon, okra, cantaloupe, cowpeas Adult size: medium-size moth; wingspan 1 – 1.3 in (25 – 35 mm) |
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Life cycle: as many as four generations per year in temperate regions; year round in tropics
Description & Life Cycle: Female moths lay eggs daily throughout their life span of seven to ten days. The minute eggs, about half the diameter of a pinhead are laid singly on both the upper and lower sides of the leaves on the host plant. They are spherical with a flat top and ribs running from top to bottom. Colour ranges from white, cream, yellow or light brown and they develop a band on the second day which darkens as time progresses towards hatching. Emerging larva are white with a brown head. They initially begin feeding in a group but as they develop through their four to six instars, they become cannibalistic and kill each other until usually one, or maybe two, larvae remain feeding on the one fruit. When the larvae are mature, they drop to the ground where they will bury themselves down two to four inches (5-10 cm) to pupate. The cylindrical pupa is fairly hard-shelled and a shiny brown colour. During the growing season in temperate regions, the pupating stage lasts ten to fourteen days before the mature moth emerges. In areas where the winters are relatively mild, the larvae will bury themselves a little deeper to pupate over the winter. Adult moths will emerge when the spring temperatures warm up…usually by late April or early May. In regions where the winters are harsher, the pupae do not survive. But the pupae are capable of entering into facultative diapause, or a state where further development is temporarily stopped. They do this in response to adverse changes in the environment such as during a severe drought. By entering diapause during adverse changes in environmental conditions, their reproductive success rate increases substantially upon the delayed emergence. Adult moths are a light buff or beige colour with maybe a tinge of olive green. Markings are quite indistinct but for suggestions of dark spots near the bottom edge. Wingspan is one to one and a third inches (25-35 mm). The moths are nocturnal and migrate seasonally. A strong wind can carry them approximately 250 miles (400 km), into regions where the winters are too cold for the pupae to overwinter.
Special Notes: Native to the Western Hemisphere, except in the coldest regions. This is a major agricultural pest in the larval stage, doing significant damage to developing fruits which adversely impacts on expected harvest yields. Best control is through integrated pest management techniques as this pest has become resistant to many pesticides. Trap crops and/or deep ploughing are effective controls. There are over one hundred predator insect species that will feed on the eggs and larvae of this pest species.
Posted on August 4, 2015 |
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Malacosoma californicum pluviale (northern tent caterpillar)
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Malacosoma californicum pluviale Class: Insecta Host plants: broad-leaved deciduous hardwood trees Adult size: moth wingspan = 1-1.5 in (2.5-3.8cm) |
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Life cycle: one generation per year
Description & Life Cycle: Young larvae emerge in spring coinciding with the leaves unfurling on hardwood trees. Timing is dependant on regional weather. Just an eighth of an inch long (3mm) and dark in colour, they are distinguishable by the white hairs covering their length. For the next 6 weeks, the larvae eat their way through 5 to 6 instar stages, moulting out of their skin as they outgrow it. With each successive shedding, their distinguishable markings become visible. Down the centre of their back is a network of uniform orange patches, in the centre of which and corresponding to each body segment, is an elliptical light blue-grey patch outlined in dark brownish-black. There are two blue-grey dots in each body segment running down both sides beneath which runs a narrow orange strip. (Note: There can be variations in the markings.) By the end of the 5th or 6th instar stage, the caterpillars measure about 1.75 – 2.2 inches (4.5 – 5.5cm) long. When they are ready to pupate at the end of the 6 weeks, the caterpillars spin cocoons of pale silk, covered in a yellow powdery dust, attached in a sheltered area of a tree or shrub. However, they will also use any convenient, out-of-the-way spot including up under the eave of the house or tool shed. The pupa is dark reddish-brown colour and measures 0.6 – 0.75 inches (1.5 – 2.0cm) long. In 14 – 21 days the adult moth emerges. Stout-bodied adult moths vary in colour from buff yellow to a dark reddish-brown. Forewing is marked with a dark line running at a right angle from the body. Two paler lines run parallel to the outer wing edge and neatly divide the forewing into three equal segments. Wingspan ranges from 1.0 – 1.5 inches (2.5 – 3.8cm). The moths do not feed and only live one to fourteen days. Their sole purpose is to mate. Once a female is fertilized, she lays 150 to 250 eggs in a sixth of an inch (1.5cm) long mass on a small diameter twig. She then encases them in spumaline – a frothy, glue-like substance which hardens and turns a glossy, dark brown colour. This protects the eggs from small predatory insects. Within three weeks, the embryos have developed into phalate larvae. At this stage, they will diapause through the winter inside the eggs.
Special Notes: Malacosoma californicum pluviale are native to North America, more commonly found in the southern half of British Columbia as far east as Quebec and in Newfoundland. Their range also reaches south into the United States, typically west of the Cascade Mountains in Washington and Oregon states. But populations have also been found in the northern parts of Montana, Idaho and several northeastern states. Young northern tent caterpillar larvae form a silky tent in the crotch of a tree branch, usually at the outer reaches of the tree crown…and there can be larvae from more than one egg mass within one tent. As the larvae grow in size, they increase the size of their silky tent. Once they reach the last instar stage, the caterpillars begin to separate from the mass and start to search out suitable pupating spots. Large outbreaks of northern tent caterpillars typically happen roughly every ten to twelve years and can last anywhere from three to six years in a row. The adult moths are nocturnal and highly attracted to lights.
Natural Controls: Predators include frogs, small mammals and a large number of different bird species. There are also a large number of insect predators including bees, wasps, flies, ants, beetles and earwigs that will prey on the northern tent caterpillar throughout various stages of its life span. During large outbreaks numerous diseases are known to develop amongst colonies of Malacosoma species which can be directly attributed to controlling their numbers. One such disease is the nuclear polyhedrus virus, also known as nucleopolyhedrosis virus, or NPV. Often, an infected dead caterpillar will be seen hanging in place from a branch by its mid-section…its body forming an inverted V-shape.
Caution: The yellow powdery dust on the cocoon can cause an allergic reaction in some people.
However, it is not unusual to see the odd mature northern tent caterpillar intermingling with a mass of forest tent caterpillars as they search for a suitable spot to pupate.
Posted on May 31, 2013
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Malacosoma disstria (forest tent caterpillar)
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Malacosoma disstria Common name: forest tent caterpillar Class: Insecta Host plants: broad-leaved deciduous hardwood trees Adult size: moth wing span = 1-1.75 in (2.5-4.5cm) |
| Life cycle: one generation per year egg – overwinter larva – 5 instar stages lasting a total of 5-6 weeks pupation – 10 to 14 days adult – 1 to 10 days
Description & Life Cycle: Young larvae emerge in spring coinciding with the leaves unfurling on hardwood trees. Timing is dependant on regional weather. Just an eighth of an inch long (3mm) and almost completely black, they are distinguishable by the hairs covering their length.
When they are ready to pupate at the end of the 5 or 6 weeks, the caterpillars spin cocoons of pale silk covered in a yellow powdery dust, usually curling up leaf. But they will use any convenient, out-of-the-way spot including up under the eave of the house or tool shed. In 10 – 14 days the adult moth emerges. |
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