Endangered Species in Santa Cruz County - Species Account


Mount Hermon June Beetle
(Polyphylla barbata)


This information was excerpted from the following publications, which are available for reference use at the Central Branch Library:


Recovery Priority 8 —

Indicates a species having a moderate degree of threat and a high recovery potential.1

Description and Taxonomy

The Mount Hermon June beetle (Polyphylla barbata) was first described by Cazier (1938) from Mount Hermon, Santa Cruz County, California. The status of P. barbata as a full species was supported by Cazier (1940) and again by Young (1988), who recently made several nomenclatural adjustments to the genus Polyphylla but retained P. barbata. The Mount Hermon June beetle belongs in the Order Coleoptera and Family Scarabaeidae.

The adult male is a cryptic small scarab beetle with a black head, dark blackish-brown elytra (thick leathery forewings) clothed with scattered long brown hair, and a striped body. Elytral vittae (stripes) are broken, often reduced to discontinuous clumps of scales, but still form identifiable lines (Cazier 1938; Young 1988). Females are larger, with a black head, chestnut-colored clypeus (plate on lower part of face) and elytra, and golden hairs on the head, thorax, and legs (Young 1988). The single adult female described was 22 by 11 millimeters (mm) (0.87 by 0.43 inches (in.)), while the holotype male was 20 by 9.7 mm (0.79 by 0.39 in.) (Young 1988). Three other wide-ranging species of Polyphylla (P. crinita, P. nigra, and P. decemlineata), occur in the Ben Lomond-Mount Hermon-Scotts Valley area. The Mount Hermon June beetle is distinguished from other species of Polyphylla by the presence of relatively dense, long, erect hairs scattered randomly over the elytra and short erect hairs on the pygidium (abdominal segment) (Young 1988).

Life History

Like other Polyphylla species, the Mount Hermon June beetle is believed to require about 2 to 3 years to mature from an egg through the adult form. However, the rate of growth of laboratory-reared larvae suggests that the Mount Hermon June beetle may complete its life cycle within one year (Hazeltine, in litt. 1994). Most of the life cycle is spent in larval stages. The larvae are subterranean and feed on plant roots. While Polyphylla larvae are generally considered to be grass and pine root feeders (Andrews, California Department of Food and Agriculture, pers. comm. 1993; Evans, Los Angeles Museum of Natural History, pers. comm. 1993), the Mount Hermon June beetle may also feed on the roots of monkeyflower, oak, fern and other plants found in the Zayante sand hills ecosystem (Hazeltine, in litt. 1993). Based upon laboratory observations, larvae may be susceptible to fungal infestations if soil conditions are too moist (Hazeltine, in litt. 1993). However, the significance of such mortality sources is unknown.

For 1 to 2 months during summer, Mount Hermon June beetles emerge as imagos (adult forms) to reproduce. Males are strong fliers, emerging from their burrows to fly low to the ground in search of females (Hazeltine, in litt. 1994). Females are thought to be fossorial, remaining just below the surface in burrows. Females may not fly due to their large body size (Evans, pers. comm. 1993 Hardy, California Department of Food and Agriculture, pers. comm. 1993). Like other Polyphylla species, males are believed to locate females by tracking female pheromone signals (Fowler and Whitford 1981; Hazeltine 1993); such a mechanism would ensure reproductive success within the limited time period for mating (Lilly and Shorthouse 1971). The flight season generally extends from mid-June to late July. The flight time of males appears restricted to evening, being observed only between 8:45 and 9:30 pm; flights may occur later during the latter part of the flight season (Hazeltine 1993).

The small mouthparts and limited flight period of Mount Hermon June beetles suggest that adults of this species do not feed (Hazeltine, in litt. 1993). Adults of the related Polyphylla decemlineata are known to feed on the leaves of trees (Johnson 1954). At the end of the flight period each evening, males burrow back into the soil, emerging repeatedly on subsequent evenings to search for mates until their nutrient reserves expire (Hazeltine 1993). Females are believed to lay eggs at the bottom of their burrows and die a short time later. The life cycle continues as newly hatched larvae tunnel from the burrow in search of roots.

Habitat Description

Habitat of the Mount Hermon June beetle is described as ponderosa pine-chaparral habitat with sandy soil and open, sparsely vegetated areas (Hazeltine 1993; Hazeltine, pers. comm. 1994; Hoekstra, U.S. Fish and Wildlife Service, pers. obs. 1994). Beetles may also occur in more vegetated areas of chaparral (Russell, Miami University, Ohio, pers. comm. 1994). Common vegetation found in these open areas includes bracken fern (Pteridium aquilinum), monkeyflowers (Diplacus sp.; Mimulus sp.), grasses, and small annual herbs (Hoekstra, pers. obs. 1994). While not always present, silver-leafed manzanita seems to be a good indicator of suitable habitat (Hazeltine 1993; Hoekstra, pers. obs. 1994) All of these descriptions are consistent with those of Zayante sand hills habitat.

Range and Distribution

Most Polyphylla species have very narrow distributions. Of 28 North American species, 20 have restricted ranges; 15 of these are endemic to isolated sand deposits (Young, 1988). The restricted distributions of these species are likely due to various factors including substrate and food preferences, edaphic tolerances, and the low mobility of fossorial larvae and females. Most Polyphylla species seem to prefer sand and grass or sand, grass, and conifer associations similar to those found in the Zayante sand hills ecosystem (Borror et al. 1976; Young 1988; Hardy, pers. comm. 1993).

The range of the Mount Hermon June beetle is restricted to the Zayante sand hills habitat of the Ben Lomond-Mount Hermon-Scotts Valley area. Historically, specimens were known only from "sandhills" at the type locality of Mount Hermon in Santa Cruz County, California (Cazier 1938, 1940; Young 1988).

Population Status

Between 1989 and 1994, Mount Hermon June beetles were collected at 28 of 43 sites surveyed. Records include results of a regional survey and incidental collections (McCabe 1991; Hazeltine 1993; Hazeltine, pers. comm. 1994; Russell, pers. comm. 1994). Twenty six of the 28 collection locations were on mapped Zayante soils in the primary cluster of the Ben Lomond-Mount Hermon-Scotts Valley area. The other two collection records were within the same area, in close proximity to mapped Zayante soils (Hoekstra 1994a). All sites were similarly characterized by sparsely vegetated sandy substrate with silver-leafed manzanita or ponderosa pine (Hazeltine 1993; Hoekstra, pers. obs. 1994). Mount Hermon June beetles were not found in surveys of suitable Zayante sand hills habitat outside the Ben Lomond-Mount Hermon-Scotts Valley area; nor were they found at locations with habitat not characteristic of the Zayante sand hills ecosystem (Hoekstra 1994a).2

Current Threats

Over 40 percent of Zayante sand hills habitat is estimated to have been lost to, or altered by, human activities including sand mining, urban development, recreational activities, and agriculture. Historically, Zayante sand hills habitat was estimated to have covered 2,533 hectares (6,265 acres) (Lee 1994). Currently, 1,459 hectares (3,608 acres) remain in a natural state (Lee 1994). Suppression of the periodic wildfires, which are probably critical to the maintenance of Zayante sand hills habitat, has resulted in increased litter and understory vegetation such that a fire may be detrimental to the survival of the Mount Herman June beetle. Fire suppression has also resulted in increased vegetation over time, possibly reducing the quality of the habitat for this species, which may prefer open, sparsely vegetated areas (Hazeltine 1993; W. Hazeltine, pers. comm. 1994; Hoekstra, pers. obs. 1994) but also may occur in more vegetated areas of chaparral (Russel, pers. comm. 1994). Pesticides and over-collection are recognized as potential threats.3

Conservation Efforts

Portions of the Zayante sand hills ecosystem are protected under public ownership in only three locations--the Quail Hollow Ranch, owned by the County of Santa Cruz; Bonny Doon Ecological Preserve, managed by the California Department of Fish and Game; and Henry Cowell Redwoods State Park (Maranglo 1985; Lee 1994). However, the Mount Hermon June beetle is not known to occur in either the Bonny Doon Ecological Preserve or Henry Cowell Redwoods State Park. The majority of Zayante sand hills habitat is on privately owned properties and is susceptible to continued sand mining and urban development. No Federal land is located in the region.

Needed Recovery Actions

The general strategies discussed in the Overall Recovery Strategy section are appropriate for these species. In particular, this species would benefit from:

  • HCPs [Habitat Conservation Plans] with quarry owners that minimize the loss of habitat from sand mining
  • HCP with County of Santa Cruz that minimizes the loss of habitat from sand mining and urban development
  • HCP with the City of Scotts Valley that minimizes loss of habitat from urban development4
  • Development and implementation of management plan for Quail Hollow Ranch County Park
  • Protection of habitat through acquisition or establishment of conservation easements
  • Conduct research focusing on habitat requirements for long-term survival (e.g., feeding behavior; requirements for larval and adult stages).5

Footnotes

1U.S. Fish and Wildlife Service. "Recovery Plan for Insect and Plant Taxa from the Santa Cruz Mountains in California." Portland, Oregon." The Service, 1998, p. 15.

2U.S. Fish and Wildlife Service. "Draft Recovery Plan for Two Insects (Polyphylla barbata and Trimerotropis infantilis) and Four Plants (Chorizanthe pungens var. hartwegiana, Chorizanthe robusta var. hartwegii, Erysimum teretifolium, and Polygonum hickmanii) from the Santa Cruz Mountains, California." Portland, Oregon. The Service, 1997, pp.16-19.

3U.S. Fish and Wildlife Service. "Recovery Plan for Insect and Plant Taxa from the Santa Cruz Mountains in California." Portland, Oregon. The Service, 1998, p. 20.

4U.S. Fish and Wildlife Service. "Draft Recovery Plan for Two Insects (Polyphylla barbata and Trimerotropis infantilis) and Four Plants (Chorizanthe pungens var. hartwegiana, Chorizanthe robusta var. hartwegii, Erysimum teretifolium, and Polygonum hickmanii) from the Santa Cruz Mountains, California." Portland, Oregon. The Service, 1997, pp. 19-20.

5U.S. Fish and Wildlife Service. "Recovery Plan for Insect and Plant Taxa from the Santa Cruz Mountains in California." Portland, Oregon. The Service, 1998, p. 21.