Preservative Treatment Against Wood Borers

Preservative Treatment against Wood Borers

Insect Pests of Standing Trees genus Anobium and the death watch The females lay eggs in grooves on the Standing trees, particularly if unhealthy or beetle, genus Xestobium, of the Anobiidae, surface of the wood, in joints which have damaged, may be attacked by a number of actually feed on the wood substance, opened slightly, or on the surface where the types of insects. consuming the cellulose and other grain has been torn in planing. The eggs Certain moths, including the Goat Moth, constituents of the cell walls. hatch into white grubs having six minute Leopard Moth and some clearwing moths, legs and when mature are about 6mm long. breed in trees. Oak, Ash, Elm and other Preventive Measures The terminal segment of the grub is rather bulbous and the whole grub is bent into a hardwoods may be attacked by the first Attack by any of the wood-destroying crescent shape. named, Pear and other fruit woods by the beetles found in Great Britain can be second and Willow and Alder by the third. prevented by adequate treatment, with a As the larvae feed on the wood they bore The injury is not to be seen until the trees suitable preservative, of the wood before galleries which become partly filled with are felled and it is too late to take action. use. The vacuum and pressure method granular wood dust which feels like very Poplars are often damaged by the large gives the maximum protection with any find sand. When fully developed, after one poplar longhorn beetle, the larvae of which timber. Permeable timbers may be to three years, the grubs or larvae approach bore more or less vertical galleries about effectively treated by the hot-and-cold open the surface of the timber and pupate. After the size of a pencil, from near the base of tank process or by prolonged soaking for the pupation period has become completed, the tree upwards to a height of 8 to 12 ft. or several days in suitable preservatives. the adult beetles bore small round exit more. Dipping, brushing and spraying with a holes about 1.5mm in diameter. The adult suitable preservative can give effective beetles are capable of flight and this Sickly confer stems, e.g. Larch and Spruce, protection if the preservative is thoroughly enables them to travel and infect other are frequently found on examination to be applied. timbers. In the period from May to the breeding grounds of either the giant September, beetles may frequently be wood wasp or the steel blue wood wasp. Common Furniture Beetle- Occasionally adult insects of these species found on the window ledges of houses emerge from scaffold planks, ladders and Anobium punctatum containing infested wood. even wood in buildings. The common furniture beetle naturally Treatment These are examples of insects which breed inhabits dead stumps and fallen branches 1. Furniture and small wooden articles may in standing trees and which may emerge in woods and hedgerows, but at the present be treated by gas fumigation but this should from newly felled wood. They are the time is found far more abundantly in the only be carried out by specialist firms. enemies of the forester and their larvae are woodwork of buildings and furniture than in rarely seen except when infested logs are its original habitats. Today it is exceptional 2.The most convenient way of treating being converted and the gallaries in which in some parts of the country to find a infested timber whether in furniture or in they are feeding are exposed. building dating back more than 20 years buildings, is by the application of an It is seldom that any insect pest of standing which is entirely free from infestation, and in insecticide solution to all parts showing timber will cause anxiety to the Great Britain most of the damage is found signs of infestation, as well as to the householder. in timber which has been in use for 10 adjacent timber. years or more. It is seldom found in Insect Pests of Converted furniture manufactured for less than that Special attention should be paid to the Timber period, although attacks sometimes occur undersides of drawers or tables, unpolished in the osiers used in basketwork of less ends of legs, and to both the inside and The more important pests, the larvae of than that age. In New Zealand, where it is outside surfaces of the backs of cabinets. which attack felled and converted timber, also a serious pest, timber is sometimes All joints or cracks, whether in furniture or in are beetles of the order of coleoptera. They infested in little more than a year after structural timbers, should be well treated. are very numerous and extremely varied in felling. their general appearance and feeding With structural timbers, dust and dirt should habits. They include some of the largest be cleaned off and surface covers such as and some of the most minute of living Description of the Beetle carpets and linoleum should be removed so insects, but relatively few species infest The adult beetles are 2.5mm-5mm in length as to give access to the timber. converted timber in Great Britain. The and are reddish to blackish brown in colour. larvae of some beetles, such as Lyctidae The first body segment (prothorax) is hood- The insect does not lay eggs painted or and Bostrychidae, derive their nourishment shaped and when viewed from above on polished surfaces but may use old flight from the starch or other carbohydrates almost completely hides the head. The holes. This can be prevented by the regular which are present in the sapwood cells for upper parts of the body are clothed with a some time after the trees are felled. Others, fine covering of short yellow hairs, and rows application of furniture polish. such as the common furniture beetle of the of small pits or punctures on the wing covers are well defined.

3. Where the attack is so severe that the Description of Beetle strength of the timber is affected it may be The death watch beetle, the largest of the necessary to replace the infested parts with British Anobiidae, measures from 6mm- new wood or plywood which should be 8mm in length. Its colour is dark chocolate treated before being used. brown with patches of short yellowish hairs, which give the insect a variegated desirable, supplemented by application with 4. The most effective time for application of appearance. In old specimens these hairs preservative paste. insecticides is early Spring to the late may have been rubbed off, in which case Summer. the mottled appearance is less obvious. 4. Search for and destruction of death watch beetles on floors or beneath infested 5. The insecticide may be used by brush, The eggs, which are white, lemon-shaped timbers during the above period. but where the timbers are not very and measure about 0.5mm in length, are accessible a spray may be required. The laid in open joints between adjacent 5.Inspection of timbers each Spring for a atomizer type of spray is not suitable. In timbers, in cracks or crevices in the surface period of years after treatment to detect any addition it is advisable to inject the of the wood, and sometimes within old evidence of continued activity in the form of insecticide into exit holes with an injector or tunnels and exit holes. fresh exit-holes or bore dust, in which case oil-can having a fine nozzle. This assists in further insecticidal treatments will be eliminating insects which are still active The larvae are curved white grubs covered necessary as long as any activity remains. inside the timber. with long fine yellowish hairs and are over 6mm in length. The phases of the life cycle Wood showing evidence of even slight 6. In some circumstances the use of heat or are the same as for the furniture beetle, but damage ought not to be re-used unless it freezing techniques can be considered. the beetles commonly emerge in April, May can be “sterilised “. New timber should be Both procedures must be conducted by or June, leaving a round exit hole about sound, adequately seasoned and free from properly trained and competent technicians. 3mm in diameter. Attack by death watch sapwood which is particularly liable to beetle can easily be distinguished from that attack by fungi and insects. When oak DEATH WATCH BEETLE – of other wood boring insects by the heartwood is used, treatment with a Xestobium rufovillosum presence of small bun-shaped pellets in the preservative is not necessary, but The natural habitat of the death watch bore dust produced by the grub. softwoods (coniferous timbers), which are beetle is in decayed parts of old trees, much less resistant to decay, should be especially willows and oaks. In buildings, Treatment given at least a surface coating with a good timber which is free from decay is rarely, if Timber infected by the death watch beetle preservative having both fungicidal and ever, attacked, the eggs being laid almost should be very carefully inspected, before insecticidal properties. If replacement invariably in more or less decayed parts of any treatment is undertaken. Such timbers are pressure treated with an the timber. Laboratory research tends to inspection should, if possible, take place approved preservative it is unnecessary to show that the duration of the larval period is during the period April to June in which the remove sapwood. affected by the extent of decomposition beetles emerge. resulting from fungal activity. Thus, POWDER POST BEETLES - Lyctidae although the average length of the larval Treatment with an insecticide by brush or (Lyctus) and Bostrychidae Lyctidae period is approximately three years, it is spray during the emergence period of the Of the lyctidae, two species namely Lyctus reduced very considerably by breeding the beetle in Spring or early Summer is useful brunneus and Lyctus linearis occur in Great beetle in wood which has already been in destroying eggs and young larvae before Britain and Northern Ireland. The former is decayed by selected fungi, the temperature they enter the wood but it is doubtful slightly the larger and by far the more and humidity of the air being controlled. The whether such treatment will kill older larvae numerous. condition of the wood appears to be working below the surface at any important both to the common furniture appreciable depth. Lyctus beetles are found in unseasoned or beetle and the death watch beetle, for recently dried hardwood timbers, the pores sometimes the infested wood will be The following is a summary of the of which are large enough to admit the deserted by the beetles on account of some recommended stages of treatment in an ovipositors of the females for egg laying. change in the condition of the timber or infected building: Oak, Ash, Elm, and Sweet Chestnut as well because of the action of predatory insects. as some imported timbers are commonly 1. Removal and replacement of actively infested. The preference of the beetle for hardwoods infested timbers, the strength of which is (although softwoods are not immune) may deemed by a competent person to have Only the sapwood is attacked as it is the account for the total damage by death been seriously affected. Strengthening of starch in this portion of the wood which watch beetle in the country being smaller such timbers to avoid their removal involves provides the food for the larvae. In timber than that due to the furniture beetle. The a risk of continued activity and spread of which has been cut for some time the larger larval size of the grub and the long attack unless insecticidal treatments are starch may be so depleted that the grubs larval period may, however, result in the also given, not only to the infested timber are unable to feed. Hence these pests are actual damage being more serious in the but also to timbers used for replacement. never found in old wood, but may be areas infested. In circumstances favouring encountered in timber yards, fencing and attack, structural timbers may be so 2. Removal of the superficial bore dust and also in comparatively new furniture if any weakened that replacement is essential. In debris from timber by scraping and the use sapwood has been included. Many cases of old churches and and other buildings of a vacuum cleaner before treating with an infestation have been reported by damage by both death watch and furniture insecticide. merchants holding stocks of susceptible beetles may be present in the same piece timbers, and the prescence of the pests is of wood. The timbers of old barns and old 3. Two applications of an insecticide by often revealed by small piles of fine powder wooden ships may also be attacked. The brush or spray during the period of April to on boards in the stacks. Kiln drying the “Victory”, Nelson’s old flagship, has been June. Annual applications during this period timber before use will sterilise it if it has very seriously infested for a number of for at least four consecutive years are been infested, but whilst any starch remains years.

in the sapwood cells renewed attack is not treatment kiln. Preventative measures are impossible. the same as for Lyctus beetles.

Description of the Beetle HOUSE LONGHORN BEETLE - The beetles are of slender form, Hylotrupes bajulus distinguishable from the Anobiidae and This was original a forest insect, breeding in well advised to call in an expert who will from the Bostrychidae by the thorax which dead branches of conifers in Southern supervise the work. To ensure immunity does not protrude over the head. Europe. As climatic conditions changed the from attack the timber must be given insect gradually spread northwards, at least treatment with a suitable preservative Lyctus brunneus is 5mm-6.5mm long and is as far as the countries bordering on the resulting in complete penetration of the of a brownish colour. The widest part of the Baltic, and at the same time spread into the sapwood by the preservative prior to its thorax is almost as wide as the abdomen. timbers of buildings to breed and feed. installation. Lyctus linearis is slightly shorter, the wing cases are more definitely marked by the Phymatodes testaceus parallel ridges and the thorax is distinctly The larvae are most active in the sapwood Another species of longhorn which causes narrower than the abdomen. The eggs are of softwoods, but although it was formerly a slight damage to the sapwood or spindle shaped and usually several are laid general belief that hardwoods were hardwoods and may spread in a timber in a single pore. The larvae are curved immune, recent cases of infestation of oak yard to stock, on which the bark is still white grubs with a yellowish head and dark and other hardwoods have been reported present. This pest is sometimes confused brown jaws and when fully grown measure from the Continent. Serious outbreaks in with the house longhorn beetle, but it is not approximately 6mm in length. The exit Great Britain were virtually unknown until a serious pest and does not attack timber in holes are about 1.5mm in diameter and are recent years, and at present are restricted buildings. usually filled with a fine flour like bore dust. to certain localities. The house longhorn beetle causes PIN-HOLE BORERS -Scolytidae and Treatment extensive damage to timbers in South Platypodidae Treatment is perforce very largely Africa. Pin-hole beetles are borers which attack preventive, directed toward discouraging freshly felled logs and possibly, in some the female beetles from laying eggs in It is known that, in England, the larval cases, sickly standing trees. They are found wood containing starch. This is achieved by period may be as long as 11 years, in which chiefly in tropical and sub-tropical forest spraying with an insecticide which is either case the damage caused in a roof member regions, and appear in a matter of a few repellent to the adult female or toxic to the or piece of joinery may be so extensive that days or even hours when felling in an area larvae as they emerge from the eggs, or only a thin shell of sound timber is left. begins. These beetles do not continue both. The grubs are similar in shape and There is very little external evidence of working or extend the damage in seasoned size to those of the common furniture infestation except that sometimes the timber. beetle, but are less bulbous at the ends and course of the borings may be detected by have more prominent breathing pores along an uneveness of the wood over them. The adults of these insects are responsible the sides. If the larvae are found in wood for the bore holes which are used to receive which has been taken into the factory or Description of the Beetle the eggs, which are deposited in niches workshop, all sapwood should be cut away The house longhorn beetle is somewhat along the gallaries. The beetles carry into and burned. It is not advisable to use flattened, measures from 8mm to 25mm in the borings the spores of certain fungi from sapwood for furniture or interior woodwork length and is brown or black in colour. The which mycelium develops in the galleries such as panelling unless it has been head and prothorax, the first body segment, and provides the food for the grubs. The effectively treated with an insecticide and is are thickly covered with grey hairs except growth of fungus in the galleries often known to be free from infestation. for a smooth central line on the prothorax, causes staining in the surrounding wood, on each side of which is a shiny black seen on the surface in the form of dark Bostrychidae prominence. On each wing cover the grey rings round the opening or bore holes. The Bostrychidae are more prevalent in warm hairs are grouped in patches which are peculiar feeding habits of the larvae of pin- countries and are of minor importance in often fused to form two transverse bands. hole borers have given rise to the name Great Britain, but may be found in some The larvae are straight-bodied fleshy white “Ambrosia Beetles”. It is characteristic that timbers imported from tropical countries, grubs, clearly divided by deep transverse the tunnels seldom contain any bore dust. particularly West Africa. folds into a number of rings or segments. Various types of galleries are made by The head is sunk in the prothorax segments different species of borers and they do not Description of the Beetle so that only the dark brown jaws are visible. usually follow the grain, but after The adult beetle may be from 3mm long, When fully grown the larvae are commonly penetrating the wood radially for a short usually dark brown or black in colour. The 18mm long but may attain a length of about distance, change direction and often take a body is cylindrical, the antennae fairly short 30mm. The grubs feed for a relatively long course at rightangles to the original one and ending in a three-jointed club. The upper time, which, however, varies to some extent possibly following the boundary of a growth part of the thorax or second segment of the as in the case of other longhorn beetle ring. This change of direction may be body projects over the head and is rough larvae, with the moisture content of the repeated two or three times. with short spines. Both the male and female wood and with the temperature. adults bore into the wood, preferring the The beetles vary in size, the smaller sapwood of ring-porous and large pored Treatment species making galleries of the diameter of hardwoods, but by far the greatest damage, Eradication of the pest is not an easy a fine needle, whilst those of the larger however, is caused by the larvae. matter, as will be obvious from what has species may be 6mm or more across. It is been said. On the Continent, roof timbers important to be able to recognise these Treatment have been treated by sealing the roof space peculiarities because the adult beetles do Any severely infested timber should be and blowing in steam. It is not advisable for not appear in converted seasoned timber, destroyed, but infestation can be controlled a householder to attempt any treatment for manufactured wood or furniture. Although by sterilising the timber with a heat exterminating this pest himself; he would be the borings are regarded as a serious defect by the merchant it is quite safe to

use timber having ambrosia beetle damage, i.e. pin-hole borings, for purposes where the surfaces marred by the pin-holes are not visible, it is unusual for the damage to be sufficiently extensive to reduce the strength of the wood to any significant extent.

Ernobius mollis It sometimes happens that building timbers, particularly rafters, are used with the bark adhering to them. If holes are found in the bark it may lead householders to think that Furniture Beetle is present. The beetle responsible is Ernobius mollis. The workings are confined to the bark and there is no risk of other parts of the wood being attacked. T5/108

For further information contact:

Property Care Association 11 Ramsay Court Kingfisher Way Hinchingbrooke Business Park Huntingdon Cambs PE29 6FY Tel: 0844 375 4301 Fax: 01480 417587 Email: [email protected] Web: www.property-care.org

The Property Care Association was formally the British Wood Preserving and Damp- proofing Association, a company limited by Guarantee: Registered No. 3280875 England