354 



Leech and Chandler: Coleoptera 



elytra piceous, pronotum piceous discally, luteous to 

 rufotestaceoua laterally; Marin County to San Mateo 

 County aquatica Blaisdell 1940 



— Last visible abdominal sternite of male with a broad 

 and rather shallow U-shaped emargination; elytra 

 piceous, luteous or bicolored 2 



2. Discal 3rd of pronotum piceous, sides luteous to 

 rufotestaceous; elytra piceous, or piceous near suture 



and luteous laterally; Del Norte County 



nunenmacheri Wolcott 1922 



— Pronotum luteous, or with a semicircular darker area 

 showing through from underside of apex, above head; 

 elytra luteous, apices piceous; San Francisco Bay 

 region apicalis LeConte 1866 



REFERENCES 



BEERBOWER, FRED V. 



1944. Life history of Scirtes orbiculatus Fabricius 

 (Coleoptera : Helodidae). Ann. Ent. Soc. Amer., 36: 

 672-680, 1 pi. 

 BEIER, M. 



1949. Koerperbau und Lebensweise der larve von 

 Helodes hausmanni Gredler (Col. Helodidae). Eos, 

 25: 49-100, 17 text figs. 

 1952. Bau und funktion der Munderzeuge bei den Helodi- 

 den-larven (Col.). Trans. DCth Internat. Congress Ent. 

 (Amsterdam, 1951), 1 (Sect. 1): 135-138, 2 figs. 

 BLAISDELL, F. E. 



1940. A new species of Helodes from Marin County, 

 California (Coleoptera : Dascillidae). Ent. News, 

 51: 190-191. 

 GOOD, H. G. 



1924. Notes on the life history of Prionocyphon limbatus 

 Lee. (Helodidae, Coleoptera). Jour. N.Y. Ent. Soc, 

 32: 79-84, pis. VIII and IX. 

 HORN, G. H. 



1880. Synopsis of the Dascyllidae of the United States. 

 Trans. Amer. Ent. Soc, 8:76-114, 1 pi. 

 KEMPERS, K. J. W. BERNET 



1944. De larven der Helodidae (Cyphonidae). Tijdschrift 

 voor Ent., (1943), 86: 85-91, 38 figs. (Published 

 April 7, 1944). 

 KRAATZ, W. C. 



1918. Scirtes tibialis, Guer. (Coleoptera-Dascyllidae), 

 with observations on its life history. Ann. Ent. Soc. 

 Amer., 11: 393-400, pi. XXXV. 

 LAESSLE, ALBERT M. 



(information in letters, 1954). 

 LEECH, H. B. 



1955. A new genus for Cyphon robustus LeConte (Cole- 

 optera : Helodidae). Pan-Pac. Ent., 31:34. 

 LOMBARDI, DINA 



1928. Contributo alia conoscenza dello Scirtes hem- 

 isphaericus L. (Coleoptera-Helodidae). Boll. Lab. 

 Ent. Bologna, 1: 236-258, 11 text figs. 

 OSTEN SACKEN, R. 



1862. Descriptions of some larvae of North American 

 Coleoptera. Proc Ent. Soc Phila., 1: 105-130, pi. I, 

 {Prionocyphon discoideus, pp. 115-118, no figs.) 

 PEYERIMHOFF, P. DE 



1913. Le double type larvaire de Prionocyphon ser- 

 ricornis Mull. (Col. Helodidae). Bull. Soc Ent. 

 France, (1913), No. 6, pp. 148-151. 

 PICADO, C. 



1913. La larve du genre Scirtes. Bull. Soc. zool. Fr., 

 37: 315-319. ("Paru le 31 Janvier 1913".) 

 POPHAM, E. J. 



1954. A new and simple method of demonstrating the 

 physical gill of aquatic insects. Proc. Roy. Ent. Soc. 

 London (Ser. A), 29: 51-54, 1 text fig. 



of 1880. Examples of about a dozen undescribed species from 

 California have been seen. Despite couplet 2 of the above key, 

 color is probably not of value as a primary character in distin- 

 guishing species. 



PRATT, F. C. 



t907. Notes on "punkies." (Ceratopogon spp.). U.S.D.A. 

 Bur. of Ent., Bull. 64: (2+) 23-28, text figs. 3-6. 

 SNOW, WILLIS E. 



1954. (Dr. Snow kindly provided data from his unpub- 

 lished thesis.) 

 TREHERNE, J. E. 



1952. The respiration of the larva of Helodes minuta 

 (Col.). Trans. IXth Internat. Congress Ent. (Amster- 

 dam, 1951), 1: 311-314, 1 text fig., 2 tables. 

 WALSH, B. D. 



i862. (as quoted in Osten Sacken, q.v.) 

 WINTERSTEINER, F. 



1913. (as reported in) Proceedings of the New York 

 Entomological Society. Jour. N.Y. Ent. Soc, 21: 90. 

 WOLCOTT, A. B. 



1922. A new species of Helodes (Helodidae, Col.). 

 Bull. Brooklyn Ent. Soc, 17: 94. 



Family DRYOPIDAE" 



Dryopids (fig. 13:49a) are usually moderately small 

 (8 mm. or less), dull silver gray, black, or brown 

 beetles found crawling about upon the bottom- of 

 streams. They vary from semi- to truly aquatic al- 

 though none can swim. The claws are usually large 

 and adapted for holding on to the substrate. In most 

 species the head may be retracted into the thorax, so 

 that the mouth parts and most of the antennae are 

 hidden. Thus only the front of the head and part of 

 the eyes are exposed. 



The larvae are elateroid. The body is long and 

 cylindrical with the integument smooth. Abdominal 

 tergites form a complete ring except for a narrow 

 ventral groove on the first five segments. Ninth seg- 

 ment with caudal chamber is closed by an operculum 

 but without gills or prehensile hooks. 



Re spiration.— The adult beetles have an air reser- 

 voir beneath (he elytra as do most aquatic beetles 

 but they seldom ascend to the surface to replenish 

 their air supply as do those of many other families. 

 Instead they depend largely upon oxygen obtained by 

 diffusion while submerged. Much of the body and legs 

 are covered by hydrofuge tomentum or pile which 

 surrounds them with a blanket of air. Into this blanket 

 oxygen diffuses from the water, and carbon dioxide 

 diffuses outward. Since they usually inhabit well- 

 aerated running streams, it seems that oxygen obtained 

 in this way is sufficient to maintain their unhurried 

 activity. In addition they are frequently observed to 

 pick up small bubbles of oxygen produced by aquatic 

 plants during photosynthesis. They are often found 

 clustered under rough, irregular stones which have 

 trapped small bubbles of air in the crevices on the 

 underside. 



None of the known dryopid larvae of North America 

 have caudal gills. All have the usual lateral spiracles 



"After this manuscript was sent to the printer, Hinton's redef- 

 inition of the family appeared (Proc. Zool. Soc. Lond., 125: 

 565-566. November, 1955). He writes that "... a large section of 

 the family (Sostea and allied genera) is strictly terrestrial in the 

 adult stage." He states that the larvae of Dryops and Helichus 

 have been taken in the soil or in decaying wood, and that the 

 spiracles of the mesothorax and first eight abdominal segments 

 are functional in all instars in the known dryopid larvae. 



