Spruce sawflies are various

sawfly Sawflies are the insects of the suborder Symphyta within the order Hymenoptera, alongside ants, bees, and wasps. The common name comes from the saw-like appearance of the ovipositor, which the females use to cut into the plants where they lay ...

species found in North America that feed on

spruce A spruce is a tree of the genus ''Picea'' (), a genus of about 35 species of coniferous evergreen trees in the family Pinaceae, found in the northern temperate and boreal (taiga) regions of the Earth. ''Picea'' is the sole genus in the subfami ...

. There are multiple species of sawflies known as spruce sawflies, including species in the genera ''

Gilpinia ''Gilpinia'' is a genus of sawflies belonging to the family Diprionidae. The species of this genus are found in Europe and Northern America. Species: * ''Gilpinia abieticola'' (Dalla Torre, 1894) * ''Gilpinia catocala ''Gilpinia'' is a genus ...

'', ''

Pikonema ''Pikonema'' is a genus of sawflies belonging to the family Tenthredinidae Tenthredinidae is the largest family of sawflies, with well over 7,500 species worldwide, divided into 430 genera. Larvae are herbivores and typically feed on the foli ...

'', ''

Pristiphora ''Pristiphora'' is a genus of sawfly in the family Tenthredinidae. Some of its species, such as the larch sawfly ''Pristiphora erichsonii ''Pristiphora erichsonii'', the larch sawfly, is a species of sawfly. The adult sawfly resembles a black ...

'', and ''

Cephalcia ''Cephalcia'' is a genus of insects belonging to the family Pamphiliidae Pamphiliidae (sometimes incorrectly spelled Pamphilidae) is a small wasp family within Symphyta, containing some 200 species from the temperate regions of North America ...

''. Each kind of sawfly attacks particular parts of the spruce as

larva A larva (; plural larvae ) is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle. The ...

e during different times of the year.

Yellow-headed spruce sawfly, ''Pikonema alaskensis''

The yellow-headed spruce sawfly, ''

Pikonema alaskensis ''Pikonema'' is a genus of sawflies belonging to the family Tenthredinidae Tenthredinidae is the largest family of sawflies, with well over 7,500 species worldwide, divided into 430 genera. Larvae are herbivores and typically feed on the foli ...

'', is widely known in the northern United States and Canada as a destructive pest of

.Shenefelt, R.D.; Benjamin, D.M. 1955. Insects of Wisconsin forests. Univ. Wisconsin, Coll. Agric., Exten. Serv. – Experiment Sta. and Wisc. Conserv. Dep., Madison WI. 110 p. It attacks white,

black Black is a color which results from the absence or complete absorption of visible light. It is an achromatic color, without hue, like white and grey. It is often used symbolically or figuratively to represent darkness. Black and white have o ...

Norway Norway, officially the Kingdom of Norway, is a Nordic country in Northern Europe, the mainland territory of which comprises the western and northernmost portion of the Scandinavian Peninsula. The remote Arctic island of Jan Mayen and t ...

, and Colorado blue spruces. The larvae at first prefer new foliage, but after becoming about half-grown, old needles are included in their diet too. Young plantations become susceptible a few growing seasons after establishment. The insect overwinters underground as a larva in a dark-brown papery cocoon encrusted with soil (Rose and Lindquist 1985).Rose, A.H.; Lindquist, O.H. 1985. Insects of eastern spruces, fir and, hemlock, revised edition. Gov’t Can., Can. For. Serv., Ottawa, For. Tech. Rep. 23. 159 p. (cited in Coates et al. 1994, cited orig ed 1977) In the spring, the cocoon changes into a pupa, from which the adult emerges, mainly in May or June at about the time the spruce bud scales are sloughed off. The spring-emerging females lay their eggs in shallow slits at the base of expanding needles, generally 1 per needle. Hatching takes place in 6 to 14 days, and the larvae feed in groups on the new needles until only short, brown stubs are left, after which the larvae move back on the twig to feed on the older needles until they are full-grown—usually in late July or early August. Larvae drop to the ground and spin overwintering cocoons. A single generation occurs per season. Larvae are about 20 mm long when fully grown, and have chestnut-brown to reddish-brown heads. The body is yellowish-green above, lighter beneath, with a double row of broad, brown to olive-green stripes along the back, with another green stripe on each side. A small spot occurs near the legs on all but the rearmost section of the body. In spite of the large numbers of parasites that attack this sawfly, planted spruce can be heavily damaged. Any

insecticide Insecticides are substances used to kill insects. They include ovicides and larvicides used against insect eggs and larvae, respectively. Insecticides are used in agriculture, medicine, industry and by consumers. Insecticides are claimed to b ...

would maximize larval mortality when applied about 10 days after bud caps have been shed, but when only few trees are infested, the larvae can be picked off by hand. Other than in young plantations, this sawfly generally causes little or no mortality of trees in spite of its widespread presence.

Green-headed spruce sawfly, ''Pikonema dimmockii''

The green-headed spruce sawfly, ''

Pikonema dimmockii ''Pikonema'' is a genus of sawflies belonging to the family Tenthredinidae. The species of this genus are found in Europe and Northern America. Species: *''Pikonema alaskensis ''Pikonema'' is a genus of sawflies belonging to the family Tent ...

'', is closely related to the yellow-headed spruce sawfly, with which it has a similar distribution, but occurring most commonly from Saskatchewan eastward. Damage by this insect is rarely seen, and the life cycle is similar to that of the yellow-headed spruce sawfly.

Little spruce sawfly, ''Pristiphora lena''

The larvae of the little spruce sawfly, '' Pristiphora lena'', feed on spruce needles in June and July. The insect has been reported from Ontario and Newfoundland, but damage has been inconsequential. The larvae are black-headed until almost fully grown (about 10 mm long) when the head colour changes to reddish brown. The life history is similar to that of the other spruce sawflies.

Spruce webspinning sawflies

A number of webspinning sawflies feed on spruce, but most of them are rare and solitary feeders, '' Cephalcia fascipennis'' being the most common. It occasionally causes damage to ornamental spruce trees or hedges across Canada and the northeastern United States. The larvae

overwinter Overwintering is the process by which some organisms pass through or wait out the winter season, or pass through that period of the year when "winter" conditions (cold or sub-zero temperatures, ice, snow, limited food supplies) make normal activi ...

in cells in the ground and pupate in the spring. The adults soon emerge and the female lays green cylindrical eggs singly or in end-to-end rows of 2 to 4 on the needle. On hatching, the larvae construct shelters of silk and excreta at the crotch of a twig and branch. The larvae forage from these shelters by cutting the older needles and eating them from the base outwards, usually leaving the tips of the needles which may be incorporated into the shelters. Larvae of this family typically have elongate antennae, bear a pair of jointed appendages at the posterior end, and lack abdominal legs. The colour is variable, but the head is usually dark and the body brownish with a reddish line along the back. Full-grown larvae, about 25 mm long, drop to the ground to overwinter.

References

{{Reflist Tenthredinoidea Insect common names