Bombus vosnesenskii (yellow-faced bumble bee)
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Bombus vosnesenskii Family: Apidae Adult size: Queens: 0.7 – 0.8 in (18-21 mm) Type: Beneficial |
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Life cycle phases: Description: The yellow-faced bumble bee has short, even hair and a short, square face. The fringed hairs on their hind legs form the pollen basket, called the corbicula. Antennae are medium length on the queen and females (workers), longer on the males (drones). The eyes on the queen, females, and males are all of similar size and shape. All of them are patterned with black and yellow hairs. The females and queen are relatively identical in colouring with black thoraxes marked with yellow strips at the head and the T4 segment of their thorax. Colouring on the males is almost the same but varies with more yellow on their sides which extends further up the back on their thorax. Males also have an additional yellow stripe on their abdomen and no pollen sacs on their hind legs. They also do not have a stinger. Only the female workers and queens have a stinger…which is barbless, meaning it can be retracted and extended again and again…allowing them to sting multiple times. However, in general, bumble bees are not aggressive, therefore unlikely to sting unless their nest is disturbed.
Special Notes: One of about 40 species which are native to the west coast of North America, Bombus vosnesenskii is found in British Columbia, Canada…south to Baja, California and Mexico…and touches into western Nevada. Due to their large size and hairy bodies, they are able to fly in cold, damp weather which makes them a very important early pollinator in our gardens. This species has been a popular pollinator for the commercial greenhouse trade, especially for tomato growers. Even so, the extent of urban sprawl has impacted on nesting density of this bumble bee species. Where once Bombus occidentalis (western bumble bee) was the most common species, diseases brought to this part of the country by commercially-raised bees from eastern United States, has infected the population of B. occidentalis almost to the point of extinction. Now Bombus vosnesenskii is the most commonly seen bumble bee on the west coast.
Bumble Bee Life Cycle Queens are the only bumble bees who survive at the end of the season. After mating, they search for a suitable spot where they will hibernate through the winter. Emerging in late winter or early spring, depending on the bumble bee species, the queen begins foraging for nectar and pollen. Nectar is vital for energy during this chilly period. Pollen is for the replacement of her body fats, plus it provides protein for the maturing of her ovaries. Once she has secured enough pollen for those purposes, she will collect it to horde for feeding her offspring. Supplying plants in your garden such as early spring crocuses, winter heathers, rosemary, pussy willow, berberis (barberry), mahonia (Oregon grape), and daffodils will ensure a food supply for these early pollinators. When the queen has fed and she is ready to lay her eggs, she searches for a suitable nesting site. This is almost always underground, and typically, they will utilize an abandoned mouse hole. However, they have been known to nest in tussock-type grasses and wooden bird nest boxes. Once a nest site has been selected, the queen builds a small wax cup which, when complete, she fills with nectar. This will be her food supply for the duration of her egg incubation period. A second wax cup is constructed and a mound of pollen, called a pollen ball, about one inch (2.5 cm) in diameter is built inside the cup. The queen lays her eggs…usually 200 to 300, but sometimes as many as 500…on the pollen ball, which will be the food source for the larvae when they hatch. Bumble bee eggs are poikilothermic, meaning they are not able to regulate their own temperature independently of the ambient air. The queen must, therefore, incubate her eggs. To do this, she lays her abdomen on the clump of eggs and begins vibrating the muscles in her thorax. Once heat has built up…which can take up to 15 minutes when the ambient air is only 6 °C (43 °F)…she transfers it from her thorax to her abdomen where it will warm the bald patch located on her underside. Naturally, the queen must leave her eggs for short periods of time in order to feed from her nectar cup. During the time it takes the queen to sate her appetite, the temperature of her eggs will have dropped to the ambient temperature level. These periods of temperature drop do not have any adverse effect on the development of the young larvae, however. Four days after the eggs are laid, the larvae hatch and begin feeding on the pollen ball. The queen continues to incubate the larvae, leaving them only when she must feed herself. This is when the queen is likely to leave the nest again, if she has run out of nectar in her wax cup. The larvae will moult three or four times as they continue to eat and grow over the next two weeks. At the end of that time, the larvae transform into pupae. During this stage, the larvae go through metamorphosis to change from a grub-like larva into an adult female bumble bee. This first generation of female workers then take over incubation and feeding duties from the queen, who in turn, focuses on laying more eggs through into mid-summer. With subsequent generations of workers becoming adults, the work duties are split. Some workers head out to forage, traveling as far as 3.2 km (2 mi) from the nest as they forage for flower nectar and pollen. The rest of the workers remain in the nest to rear the young, clean the nest, and maintain the temperature of the nest…either by producing heat through their thorax and sending it out from their abdomen or cooling the temperature by fanning their wings near the entrance to the nest. Come mid-summer, the queen lays fertilized eggs, which will grow into new queens, and unfertilized eggs which will grow into males (drones). These specialized adults emerge from the nest in late summer and do not return to the nest. The males lay their scent on plant material relatively near the ground, in the hopes of attracting a new queen with which to mate. Once a queen is fertilized, the male will die soon afterwards and the queen begins her search for a good hibernation spot to wait out the coming winter.
Hibernation emergence by species: Bombus vosnesenskii – yellow-faced bumble bee
Posted on March 24, 2017 |
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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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Archaeognatha (bristletail)
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Archaeognatha Family: Machilidae Common name: bristletail; jumping bristletail Adult size: 6 – 20 mm |
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Type: Beneficial Description: Bristletails have an elongated body, roughly cylindrical in shape. The thorax shows a definite hump and their whole body is covered in thin, tiny scales. Large compound eyes meet in the middle of the head and there are three ocelli, or little eyes…simple, light detecting organs. Their most unique feature…the one which sets them totally apart…is their mouthparts. It is unusual because their mandibles are monocondylic…they connect to the head in only one place. The mandibles of all other insects are dicondylic…they connect to the head in two places. Usually grey or brown in colour with distinctive mottling, they have six legs, two long flexible antenna, and three long tails with the middle one being the longest. There are several small, bendable “styli” found in the middle and hindmost sections of the body which are thought to be rudimentary appendages. They also have eversible membranous vesicles…sacs which are capable of extending and turning inside out…along both sides of their body which are specifically designed to absorb water, or moisture from their environment. There is little metamorphic change during the nymph stages, once the eggs have hatched. Archaeognaths progressively molt through six instar stages to reach adulthood and most references claim they can live anywhere from four to eight years. Sexually, the Archaeognaths are also a little different. Males and females do not copulate to reproduce. Rather, once they reach sexual maturity…possibly taking as long as two years…the males produce a string of spermatophores (tiny packets of sperm) on a spun thread from their abdomen. The threads are somewhat haphazardly attached to the substrate in locations where a female is likely to stumble across it…although there are some species where the males will do a courtship dance to entice a female to their spermaphores. The aroused female picks up a packet of sperm and deposits it on her ovipositor. Depending on the species, the female will lay her eggs in a suitable crevice…either singly or in batches of up to thirty eggs.
Special Notes: There are approximately 350 or more species of bristletails worldwide. They are found on every continent…including the Arctic and Antarctica. Of particular note…when molting the bristletail must first anchor themselves to the substrate. But if the fecal material they use as an anchoring cement to hold themselves in place through the molting process should fail to hold, the bristletail is not able to complete its molt and will die.
Posted on November 24, 2016
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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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