VOL. 54, NO. 1, JANUARY 1978 
71 
Although C. falli adults have been recovered in several areas in Orange County none 
were trapped at the Olive location. The data at Riverside show that fewer but equal 
numbers of adults were trapped in the 3 earlier years followed by a substantial increase in 
1977. Catches of C. falli adults in 1977 were also the largest in July and August, each 26% 
of total, and due apparently to the hot days and 70-75°F temperatures between 8 to 10 p.m. 
This insect has for years been a destructive pest of potatoes and of various vegetable 
crops in southeastern U.S. — M.W. STONE, 131 Sir Damas Dr., Riverside, CA. 92507 and J. 
WILCOX, 7551 Vista Del Sol, Anaheim, CA. 92807. 
SCIENTIFIC NOTE 
Abundance of house dust mites, Dermatophagoides., in elementary schools of Orange 
County, California. — House dust mites of the genus Dermatophagoides (Pyroglyphidae), 
notably D. farinae Hughes and D. pteronyssinus (Trouessart), are the most important ar¬ 
thropods producing allergens present in house dust in homes. Only 2 investigations have 
dealt with the occurrence of these mites in structures other than human dwellings. 
Oshima (1964, Jap. J. Sant. Zoo. 15: 233-44) found Dermatophagoides spp. to be dominant 
on floors of elementary and high school s in Japan, while Nakada and Yoshikawa (1976, 
Ann. Rep. Tokyo Metro. Res. Lab. P.H. 27: 264-69) recovered 3 Dermatophagoides spp. from 
seats and floors of 12 Tokyo theaters, noting that D. farinae and D. pteronyssinus were 
among the most common Acari collected. 
The abundance of Dermatophagoides mites was determined in Orange Co. elementary 
schools as part of an investigation to determine sources of allergenic materials in these 
schools. Nine schools, each with shag carpeting, were individually sampled early in the 
school year (Oct. 1976) and again later (Mar. 1977). Samples were collected by vacuuming 
a 5m 2 surface area of the floor for 5 min with a house dust concentrator (Furumizo, R. T. 
1975, Calif. Vect. Views 22: 19-27) attached to a Hoover portable vacuum cleaner Model 
S1015. After each minute the concentrator was replaced with a clean one to avoid clog¬ 
ging. During a school visit, 6 such areas were sampled, each taken from a different class¬ 
room. After sampling, the concentrator was placed in a 300ml specimen jar to which 65% 
ethyl alcohol was added. The volumetric washing technique (Furumizo, 1975, loc. cit.) was 
used to separate and isolate mites from dust in the laboratory. 
Results showed that 6 of the 9 schools sampled yielded mites (mean of 4 mites/5 m 2 
area; range = 1-9) of which 62% of the specimens were D. pteronyssinus, with the remain¬ 
ing being D. farinae. Two schools yielded both species, while the remaining 4 were singly 
infested with D. pteronyssinus. For the Oct. samples, 69% of D. farinae collected were live, 
while 41% were live D. pteronyssinus. The Mar. samples yielded no specimens of D. 
farinae, while just 4 schools were infested with D. pteronyssinus. The low mite numbers 
found in these schools as compared to 93% of nearby Orange Co. homes being infested 
with Dermatophagoides spp. which yielded a mean density of ca. 400 mites/5 m 2 area 
(Lang, J. D. and M. S. Mulla 1977, Environ. Ent. 6: 213-16), are probably due to school 
carpets being cleaned daily after school. This hygienic practice would probably remove 
mites as well as reduce human skin scales and other food detritus they feed on. The much 
lower mite numbers occurring in schools in Mar. as compared to Oct. is probably the re¬ 
sult of seasonal conditions, since the authors have previously noted that Dermatopha¬ 
goides populations decline in the spring in Orange Co. The low Dermatophagoides num¬ 
bers collected from Orange Co. elementary schools would probably thus play an insigni¬ 
ficant role in contributing to allergenic disorders present in these schools. — JAMES D. 
LANG, MIR S. MULLA, Department of Entomology, University of California, Riverside, CA 
92521 and CLAIBOURNE I. DUNGY, Department of Pediatrics, California College of Medicine, 
University of California, Irvine, CA92717. 
The Pan-Pacific Entomologist 54:71. January 1978 
