G. W. FRANKIE

Adults of cypress bark moth.

The cypress bark moth is frequently found infesting cones and trunks of Monterey Cypress in central coastal California. CYPRESS BARK Larval feeding on cones produces un- sightly accumulations of frass, while trunk feeding results in the production of swell- ings and resin flow. Primary concern about ON MONTEREY the moth may lie in its .relationship with a serious fungus disease on the cypress, ac- cording to these studies.

HE CYPRESS BARK MOTH, Laspeyre- carpana Heinr., frequently found associ- cardinale Wagener and lacerated with a sia czLpressana (Kearf.) , is a com- ated with Laspeyresia in the same cone, knife. (The inoculation and slash were monT insect associated with cypress trees, feeds only on the seeds of unpollinated considered separate test sites.) The sec- found only in California, where it occurs cones. This characteristic seed feeding ond branch was left untreated. The fun- from Mendocino County to San Diego has probably been mistaken by previous gus inoculation and knife slash were County. Its principal host is Monterey investigators for that of Laspeyresiu, made approximately two months prior to Cypress, Cupressus macrocarpa Hartw. since the larvae of both often infest the the caging. At the time of moth caging, ex. Gord., which is grown extensively same cones. Laspeyresiu, however, feed the infections had not developed into can- along the coast as a hedge, windbreak, or on unpollinated and pollinated cones. It kers, but substantial browning of the landscape tree. In addition to several is not uncommon to find more than one phloem was observed on most trees. The other species of the genus Cupressus, Laspeyresia larva feeding in a single cages were made of nylon organdy and other known hosts include members of cone. Of almost 3000 cones dissected, were constructed to enclose the basal 2 the genera Chmaecyparis, Thuja, and 20% contained from two to five larvae. ft of each branch, together with the sec- Cryptomeria. The insect occasionally is Laspeyresia larvae also tunnel into pri- tion of trunk that included the branches. found in inland areas where suitable hosts mary branch nodes and the trunks of host The cages were opened three times to are available. trees; and occasionally may be found in make counts on the egg-laying sites and Larvae of Laspeyresia commonly tun- the smaller branch crotches. At these sites the larval invasion sites. The first count nel into the cones of cypress trees. These they feed locally on the phloem tissue, demonstrated that female moths pre- may become so severely infested that the apparently avoiding the cambium. This ferred to oviposit on the diseased and extruded insect frass, which is held feeding does not girdle trees as some pre- slashed areas of treated branches. The loosely together by larval webbing, ap- vious investigators have indicated; how- second count showed that first instar pears to drip from the cone clusters. Once ever, successive attacks at one site give a larvae attacked equally the slashed sites, inside the cones, the larvae confine their girdled appearance to the affected area the inoculated sites and the trunk region feeding activity almost exclusively to the over a number of years. On healthy, un- of each tree (the branch nodes were con- scale tissue. They feed on the seeds only damaged trees the larvae have never been sidered part of the trunk in this count). in early spring when the newly formed observed to attack the branches in areas The final count demonstrated that larvae cones are small and succulent. Another other than the nodes. However, on attacking the trunk and branch nodes cone-infesting moth, Henricus macro- branches injured mechanically or by dis- were successful 50% of the time while ease, moth larvae can be found feeding those attacking the induced wounds on Hedgerow of Monterey Cypress in San Mateo in the af€ected tissue. the branches were successful only about County, infected with cypress canker. A field study on Monterey Cypress in 3% of the time. There were no successful 1965 was designed to investigate the pre- attacks made on any of the control ferred oviposition sites, initial larval in- branches. vasion sites, and the successful sites of Larval feeding on the branch nodes infestation of trees having both healthy and trunk regions results in the produc- and damaged branches. Adult moths were tion of large amounts of resin that oozes caged on 20 trees; each cage contained from the affected areas. This unsightly two adjacent primary branches. One of material seems to attract moths which lay the two branches was both inoculated eggs at these sites year after year. The with the cypress canker fungus Coryneum continued larval feeding may eventually

CALIFORNIA AGRICULTURE, JANUARY, 1967 C. S. KOEHLER

MOTH

Organdy cage used to contain adults of moth Swelling damage caused by moth larvae on on. Monterey Cypress. Thuia sp.

result in large swellings that deform the April, June, and August. Each of these the fungus. Trees attacked only by the branches at these nodal areas. The trunks peak periods is followed by a period in moth larvae apparently suffer little from are affected to a lesser extent. Some hosts, which many of the eggs are parasitized the infestation. for example Thuja, may receive attacks at by a Trichogramma wasp. The female moths may possibly play almost every branch crotch on the tree. a role in the dissemination of the fungus This results in severe swellings along the Fungus association spores. The spores are known to remain branches. Cupressus macrocarpa and several viable for almost two years under certain other Cupressus species are susceptible to conditions. The acervuli, or small pus- Seasonal activity a disease caused by the fungus, Coryn- tules in which the spores are produced, Laspeyresia has two generations each eum cardinale. Monterey Cypress is the are common on all cankered branches; year. The population overwinters as most severely affected Cupressus species these open widely during the cool wet larvae and to a lesser extent as pupae. In so far investigated. This disease has the months of winter and spring. It is con- January, the larvae which have been feed- ability to kill young cypress trees within ceivable that female moths, in their ing continually during the early winter a few years after infection. The death of search for egg-laying sites during spring, begin to pupate. Adult females, emerging a cypress by Coryneum can best be ob- may walk over these acervuli and pick up from these overwintering individuals, served on trees located away from the some of the spores on their appendages. mate and lay their first eggs during the immediate coast. [Jpon moving to another tree they may middle of March. The resulting larvae An obvious symptom of the disease is deposit some of these spores on unin- (spring larvae) increase in size and num- the formation of cankers on the trunk and fected sites. Female moths probably visit ber from March to August. At the end of branches, from which copious amounts of several trees before dying since most can- August the mature spring larvae begin to resin exude. These diseased areas are kered areas have only 5 to 10 unhatched pupate. This is the beginning of the sec- highly attractive to Laspeyresia adults as eggs at any one time, and laboratory ond pupal period which extends from evidenced by the presence of their eggs studies have dEmonstrated the moth's August to October. In mid-September the at these sites. The resulting larvae are ability to deposit up to 260 eggs over a first larvae of the second generation ap- able to successfully feed and mature in 10-day period. Since the spores can re- pear. These larvae and many of the late the necrotic tissue of the canker. Often main viable for a long period of time, it is spring larvae will overwinter in the larval larvae will be found in cankers which are possible that the disseminated spores may stage. There is a noticeable overlap be- on branch sites away from. the nodal germinate at some later time when an tween the spring and fall generations. areas. It is only under these circum- injury to the bark is incurred. This bark The eggs, which appear as small ovoid stances that the larvae can feed and de- injury may result from insect feeding, discs, are laid singly on suitable cone, velop away from the trunk or branch mechanical damage, or rapid tree growth branch and trunk surfaces. Females are nodes. causing deep bark fissures. Rain splash suspected of mating only once during The moth larvae are not suspected of is probably another means of disseminat- their lifetime since a number of female contributing appreciably to the decline ing the spores. moths, mated in the laboratory, showed of the trees due to their localized feeding the presence of only one sperm sac when habit. Thus, some of the reports in the G. W. Frankie is Graduate Research dissected after death. Egg laying is con- literature, which point to the moth as a Assistant; and C. S. Koehler is Lecturer tinuous from March to November, after tree killer, are believed to be erroneous. and Associate Entomologist, Division of which it ceases abruptly. Peak numbers Where Laspeyresia and Coryneum occur Entomology and Acarology, University of eggs are found during the months of together on a tree, the primary killer is of California, Berkeley.

CALIFORNIA AGRICULTURE, JANUARY, 1967 7