Insects infesting Pinus radiata in New Zealand

Clark, A. F. (Arthur Frederick), Govt. Printer, Wellington, N.Z., 1932

Insects Infesting Pinus radiata in New Zealand.

BY A. F. CLARK, Forest Entomologist, State Forest Service

Extracted from the New Zealand Journal of Science and Technology, Vol. XI ī T, No. 4. pp. 235-«, 1(132.

WELLINGTON, N.Z.

W. A. G. Skinner, Government Printer.

1932.

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The original publication details are as follows:

Title: Insects infesting Pinus radiata in New Zealand

Author: Clark, A. F. (Arthur Frederick)

Published: Govt. Printer, Wellington, N.Z., 1932

235

INSECTS INFESTING PINUS RADIATA IN NEW ZEALAND.

By A. F. Clark, Forest Entomologist, State Forest Service.

From the matter which follows it may at first be inferred thai Pmus . Don. in New Zealand is in danger of extermination through the action of insecl pests. The writer dors nol intend to convey at impression. When it is considered thai in this country /'. radiata is sionally poorly planted, established upon jites of wide diversity, and at times neglected so far as silviculture] measures are concerned, it is. for part, remarkably free from serious insect-attack. That th of afl ! !l continue is a matter for conjecture, and i- outside the scope of this paper, bul the facl that as yel we have no quarantine or measures designed to prevent the entry of insects infesting imported the chances of continuance for an indefinite period rather unfavourable. Many of the inserts recorded infesl only dead timber or which an in an unthrifty condition. Others, however, will be judged from superficial examination, in itherwise healthy state. The interaction of fungi and insects as yet has Keen but little studied in forestry practice in New- Zealand, and it is inly probable that in some cases the susceptibilitj of the tree to insectick has been increased primarily by the action of a fungus.

/'. radiata is a native of Monterey, California, and has been widely planted nol only in New Zealand, bill also in Australia and South Africa.

-. discussei ided into two groups, the firs! of which in-acts introduced into the Dominion, and the second oi those All the insects are described in literature, si. thai it i- nol led to redescribe them in this paper. In many cases their association with /'. radiata in this country lias not, however, been previously noted.

IDUCED [NSECTS.

Sirex noctilio Fabr.

iderable perturbation was caused some three years ago by acco of the depredations ol "I Sire» which was thru considered to be icus L. Ir is now apparenl thai < s '. noctilio Fabr. is the common in this country. The question of the identity of these two s] is hardly in a ory state, tl i ble to greal variation. Thus Chrvstal and Myers(l), upon the authority of Waterston, state thai N ,„,. ■ ;\ of S. noctilio, but nana, recently Chrystal(2) includes a -anion by Waterston in which both are treated as distinct s] and gives the following characters for their distinction: —

Females —

mb-equilateral; ssion on tergite ix distil '' dis- ... .. .. .. S. i><-

Antennae fhole or part), pedicel, and 3 :i normal ornus elong i ■ ■ distinctly Iran equal .. .. S. /'"' ncus.

,1/ ales —

Apex of abdomei -' : i segment black « Bubmetallic reflections; all femora darkened, and hj hind i seep* narrowly al brachial nei : incomplete . ■ ■ ■ - s '. noctilio.

Apex "I abdomen and all between femur and tibia striking in the hind leg). Ante] nt or pale ; I I ial oervure im omp]

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The N.Z. Journal of Science and Technology.

from the above characters tic whole of the writer's specimens are. S. noctilio a- are those in other collections which have been examined.

General account, of the inseel have been given In- Miller(3) and Clark(4), and since that time the «titer has carried out extensive Held investigations in both Islands. S. noclilio is established in all part- of tin.' Dominion, and attacks other exotic conifers in addition to /'. radiata. The attack is noteworthy upon badly suppressed trees, and those which have suffered from breakage or fire. With regard to the latter, if the trei been killed and thoroughly dried out. the attack doc- not appear to suci eed. Other predisposing factors to attack are severe infestations of Chermes pini Koch, and. possibly, damage by a fungus. In the writer'- experiei thoroughly thrifty tree is not successfully attacked. However, the condition of many plantations is by no mean- good from a silvicultural viewpoint, and. as New Zealand possesses no Siricids itself, the activities "1 N. noctilio eannol be ignored. The nature of the infestation in a stand of /'. radiata \< often of a scattered nature, and it would appear that ti dition ol tin- tree, particularly as to moisture content and quality considerable importance. A certain degree of moistui is essential, and this in turn may be connected with a fungus similar to that isolated bv Cartwrightfo).

Of the insects parasitic upon Sirex sp., the introduction ami distribution of Rhyssa persuasoria 1., has already been carried out. Biological control. however, should not lie looked upon as the sole means of checking tic insect, but rather as an auxiliary measure, to lie used in conjunction with til management and timely silvicultural operations.

pini Koch.

The effect of Chermes pini is particularly marked when combined with poor or unfavourable site conditions. A severe attack leads to marked diminution in growth, malformation of the branches, defoli and in some cases the death of the tree. The infestation is. as a general rule, very scattered, and is particularly noteworthy at times in connection with newly planted stands. The fact that a severely infested tree may be ttly found in close proximity to ether non-infested trees would show : ie ability of the insect to spread is not great. The biology of the insect tinder New Zealand conditions has not been it,-' idled, and the writer has not (with one exception) lie, ~ record its presence on any tree other than a species of the genus Pinus. It has not been found upon I'lnii. and the cycle embracing Picea and /' nus does not at i occur in New Zealand. The behaviour of the winged forms of Chermes is receiving attention.

Predatory insei ted with Chermes pini are Micromus tasmaniae Walk. Protobiella zelandica Till, and Syrphus novae-zdandiae Macq. Their is infrequent.

Hylastes /iter Payk.

This European bark-beetle «ill be the subject of a separate papi be published by the writer. The beetle breeds in the roots, stumps, and logs of /'. radiata, and in the adult stage attacks and kills newly planted trees by eating the bark tissues, mainly in the region of the ground-level ll is a serious pest in one district, and is found in both the North

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Clark. —lnsects Infesting P. radiata in New Zealand.

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{K. S. Kirby, photo. Fir.. I. —Newly planted tree killed by Hylastes aU r.

[ir. C. Darin, photo. Fig. -.— Burrows and exit-holes of Em

[nsel Insects.

Pic, .''. Damage b$ P

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Clark,—lnsects Infesting P. radiata in New Zealand.

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and South [slands. Owine to the fact that most of the stands are pure, •nal it i- proposed to clear cut and replant them, on a very .-hurt rotation in son - the insed is likely to be of serious importance in the future.

Ernobius mollis L.

- mollis, a European beetle, is found in the bark of dead standing fee- in both Islands, and is particularly prevalent in burned limber. The larvae construct burrows solely in the bark, or occasionally, when tic is thin, also in the outer surface of the wood (lie. 2). After pupation the adult cuts a small round exit-hole in the surface of the bark. The status oi this insect in Europe appears to vary considerably : so far in New Zealand it lias nor been of anything buf a secondary nature.

li, siantha maculata Blackb.

An isolated case of the attack by this weevil upon seedling plants in a nursery is recorded. The weevil is recorded from fruit-trees and vines in Australia, but has no' I n reported attacking orchard stock in New Zealand. its occurrence in the Auckland District, however, was undoubtedly due to the presence of a large orchard close to the nurse; The orchardist had noticed the weevil, hut. owing to the \fiv slight damage caused, had not reported its appearance. The adult weevils attacked the seedling pines at ground-level, causing slight loss; the larvae also were found in the seed-beds, but were causing little or no damage.

Heliothrips haemorrhoidali.s Bouche.

Feeding on a very wide variety of plants, this introduced thrip occasionally attacks the young needles of P. radiata. lis occurrence is confined to warm districts of the North Island. A second species of thrips is found 'ii the bark of dead trees, especially in moist situations, where it feeds on decaying material. This spei i iting identification.*

Indigenous !\-

Psepholax coronatus White.

This weevil is found attacking dead standing and fallen trees in the North Island. Its entrance burrow appears not unlike the exit-hole of a small specimen of one of the Sirex species at a glance, but closer investigation soon determines the point.

'.lis Sharp.

\ common native bark-beetle, /'. ventralis, is found, particularly in the Rotorua district, infesting fallen timber, in which il occurs in large numbers at rimes. Timber of a high moisture content is chosen, and a complete honeycombing effect is found with a severe infestation (fig. .'!). So far flic ondary, lan the insed may become of more - importance owing to tic ease with which it appears to have adapted itself to new condil ions.

Platypus douei Reich.

P. ānuei is found in both Islands, but is more plentiful in the North. It attacks standing dead and dying trees and fresh stumps. Burned timber is favoured, a particularly severe infestation being noted in the Wairakei

* Dr. (t. !). Morison, of Aberdeen, Scotland, haa provisionally identified tins speciea as Haplt ihri^

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Clark.—lnsects Infesting P. eadiata in New Zealand.

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district. The line shredded material resulting from the boring of the entrance-tunnel collects in heaps at the base of the tree or lodges in the crevices of the deeply fissured bark, and is a characteristic feature of the attack by this insect.

Pycnomerus sophorae Sharp: Ulonotus antarcticus White.

The connection of these insects with P. radiata is of particular interest in that beetles of the family Colydiidae are associated with the native forest and tend to die out as the forest is destroyed. Imms(6), in discussing this family, states: “ Sharp remarks that the species exhibit great diversity of sculpture and clothing, and are mainly restricted to the primeval forests. They disappear entirely when these are destroyed. New Zealand has produced 170 species, as compared with 19 found in Britain.”

P. sophorae is found, plentifully at times, under the bark of stumps in both Islands ; U. antarcticus is less common, and it will be of interest to note how many species of this interesting family will escape destruction by changing their association from the native to the exotic forests.

Torostoma apicale Broun., Phloeophagosoma sp., Tnosomus rufopiceus Broun, and Euophryum porcatum Sharp.

These small weevils are found under the bark of dead or dying standing tree-, or in stumps or logs. They occur, at times, plentifully, and mainly in the North Island.

Prionoplus reticularis White.

The largest of the native Cerambycids is commonly found in dead standing trees, logs, and stumps. It is popularly known as the huliu beetle, and is often found in burned timber, the charring of the bark being no deterrent to attack. The eggs are laid in batches beneath the bark, and the large yellowish larvae construct galleries in the wood. Tie' insect is beneficial to a certain extent, in that its extensive feeding materially assists the decay and disintegration of dead timber. The insect will attack the dead portions of living trees. This dead tissue occurs in trees which are over-mature, and arc consequently dying. The habit of the insect in attacking these portions gives rise at times to the erroneous idea that the insect is the prime factor responsible for the condition of the tree.

Navomorpha sulcatus Fabr.

The attack of this longhorn beetle has Keen noted fully by Miller (1.e.), and occurs mainly in the North Island. The wide range of hosts, including native trees, apple-trees, and P. radiata, is of interest.

Hexatricha pulverulenta Lae.

For the definite connection of this insect with P. radiata the writer is indebted to Mr. 1.. J. Dumbleton, who will be publishing an account of his observations. The beetle is found m dead standing and fallen timber, and is particularly plentiful in the Nelson District of the South Island.

Oeeetious omnivorous Meyr,

The bag-moth is commonly found upon /'. radiata in both Islands. The biology of the moth is of interest, and has been described by Hudson(7). Parasitic insects associated with the moth have been listed by Gourlay(B),

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who records Phorocei ■ feredayi Hut:.. Phorocera marginata Mutt.. Phoi nefaria Hint., and Echthromorpha intricatoria Fabr.

Some damage i by the larvae feeding upon the needles, Dul tne amount of the damage is slight in all i

isana Walk. : Ctenopseusis obliquana Walk.

These two tortricid moths cause considerable damage at i 1 tes to young -lands in doth Island.-. Tie- webbing-together and destruction of the foliage, m severe cases, lead- to the death of tie- young tree. Particularly marked i- tin.- in newly planted .-tan.l- whic thoroughly ished and an ontending with temporarily unfavourable local conditions. 'I i trees is of freq irrence, Inn Sporadic outbreaks o occur «hen onditions are favourable to the moth-. Trichogramma ~» Riley : ared In- Gourlay from tl gg-masses ol Tortrh ma, while other undetermined parasites ol both species oci

Tortricid larvae are also found boring into the stems oi young sh and probably one or both of these The point, however, requires to be determined definitely, as a third species may also be involved.

Calotermes brouni Fro

This species of indigenous termite attacks standing timber which is dead or partly d 1). The attack ha- been note,l in tie- North Island, where, owing to the similarity of ihe damage, it is confused with the more dangerous Australian termites which are ■ brought into New /,>a]and in found infesting many native ■ two other introduced timber trees. Over-mature trees and those dead portion,- of tie' trunk or limbs are subject to attack.

Eucolaspis brunnea Fabr.

Popularly known as the bronze beetle, this native Chrysomelid is well known as an orchard pest. The larvae live in the soil, and the adults, which have a wide hosl range, occasionally feed upon the needles of young /'. radiata, causing at times severe defoliation. The damage is most commonly met with in the North Island, where small localized outbreaks at times.

Odontria sp.

Species of Odontria, or grass-grubs, cause some loss in nurseries, where the larvae attack seedling plants. The total annual 'oss, however, is usually not large, although sporadic outbreaks have caused alarm. Seedlings of other exotic conifers are also attacked. The beetles oviposit in thi beds, and the larvae feed upon the roots of the young plant-. They are common, and at times serious, agricultural pests, when their control upon a large scale is by no means simple. The adult beetlea are found, upon occasions, at tacking t be needle- of ol

Stethaspis svturalis Hope.

The larvae of this large green chafer beetle have been found damaging mots of newly planted trei ularly where thi of a sandy nature. No serious loss has been occasioned, however, by this insect.

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Clark.—lnsects Infesting P. raihata in New Zealand.

( Inclusion.

From the foregoing brief notes, which record the commoner insects ted with /'. radiata, the two type- found -namely, the indigenous - which have extended their host ranee to include this tree, and the introduced insect- -are clearly defined. With regard to the former group, it i- due in part to the fact, perhaps, that the native flora includes only two pinaceous forest tree-, ami neither of these in the genus Pinus, thai tl is not greati further, that some groups usually found in fore-led -itch as the [poidea, are very poorly represented in New Zealand, ami other.-, such as the Tenthredinoidea, arc entirely absent. On the other hand, the list of introduced insects is growing steadily, as may lie expi The Dominion, while enjoying a large degree of ic isolation, must, through volume of trade with other countries, from time to time unwittingly import insect- infesting both raw and manufactured products, not all of these introduced rtunately, becoming established. The er can do a ureal deal to help safeguard the exotic forests, and much will depend in the future upon the wisdom and promptness with which the various phases of forest - management are carried out. 1' entomology i- closely linked with silviculture, and neglect of the lattei produce problems in the future with which the forest entomologist is unable to deal without scrapping the whole of the working-plan which should form the basis of management.

Tin' fact that /'. radiata. in common with many other trees which are from their native habitat and planted in a new environment, maintains ii fast rate of growth upon man} rell known. The apparent adaptability of this tree, which has been established upon sites the soil of which ranges from pure sand to impacted glacial shingle, has led in some 'n a belie! that, so fur us the usual methods of silviculture are concerned, tin- tui' can succeed with the minimum of attention. Such .-in attitude, especially in dealing with large pure stands, i- one (hut cannot lie adopted with safety. Already the loss of increment in .-nine areas, due solely to neglect, is severe : and, further, the condition of .-nine stands has been rendered such thai mi outbreak oi a serious foresl insect pes! would [ifhcult matter with which to cope. Measures designed to minimize the eh,nice of such an outbreak should I"- adopted where future forest operations are concerned.

References.

(1) Chbystal, R. N-, and Myers, J. G.: Natural Enemies ol mens Fain-, in England, and theii Life-history. Bull, Ent. Res., Vol. 11. pp. 117-77. 1928.

(2) Chbystal, R. X. : The Sirex Wood Wasps and their Importance in Forestry. Bull. Ent. Res., Vol. 14, pp. l' 1928.

(3) Milleb, I'. : Fori ' and Timber Insects. N.Z. Stair Foresl Service. Bull. No. :.'.

i!) Clark, A. !■". : The infestation of Sin •■ juvencus in Canterbury. Te Kura \ 2. pp. 10-16. 1027.

(5) Cautwriqht, K. : Notes on a Fungus associated wi . Ann. App. Biol., Vol. 16, No. I, pp. 182- 187.

(6) I'.hi-.. A. I). : General Text-book of Ento logy. 2nd ed., p. 298. 1929.

,'T Mi dbos, G. V.: Butterfli ind Mollis of New Zealand, pp. 212 211. Mil's.

: !:i,\y. E. S. : Pi in New Zealand. N.Z. Dept. of Sci. and Indus. R lull. No. 22. 1930.

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