CHIGGERS — FARRELL 137 



Ecology: According to Mr. Neil D. Richmond, the Marmota 

 collected on Apr. 19, 1948 was taken in an orchard. The chiggers 

 v/ere attached in hair follicles on the back and sides of the host. 



Cultures: A single culture (No. 61) was established with the 

 orange colored nymphs of E. marmotae. 



Date established: May 2, 1948. 



Container: Large, wide-mouth jar, 140 mm. by 135 mm., with 

 plaster-charcoal base. On June 23, 1948, a wide-mouth pint jar 

 completely lined with plaster-charcoal. On Aug. 24, 1948, a special 

 plaster-charcoal lined vial. 



Medium : Natural forest soil about 20 mm. in depth. On June 



23, 1948, soil. On Aug. 24, none. 



Source: About 130 nymphs from larvae engorged on Marmota 

 m. monax collected Apr. 19, 1948. 



Food offered: Before June 23, only the organisms contained 

 in the soil medium. After June 23, Aedes aegypti eggs and May 

 fly eggs in addition to the contained soil organisms. After Aug. 



24, Aedes aegypti eggs. 



Results: Nymphs disappeared into soil. One seen on May 21. 

 Flooded culture with water on June 23 and recovered 48 active 

 nymphs. Transferred nymphs to new container. Nymphs were 

 observed regularly in the new container. On June 29 May fly eggs 

 were placed in the culture. About 10 nymphs tried to feed on the 

 May fly eggs. At times the contracting and expanding trombi- 

 culid feeding motion of the body occurred but no other evidence 

 of feeding was detected. On June 30 no nymphs were in sight 

 when the container was opened; but many soon appeared. One 

 approached a mass of May fly eggs and seemed to try to feed. 

 Body contractions and expansions occurred; but no other evi- 

 dence was detected. On Aug. 24 the culture was flooded and four 

 living nymphs were recovered. Onychiurus sp. also were recov- 

 ered. Aedes larvae soon were active in the flotation. Nymphs 

 transferred to new container. In the special vial no feeding at- 

 tempts were observed. Nymphs were last observed alive on Aug. 

 31. All were dead on Sept. 6, 1948. 



Life history: From the data of Culture 61, E. marmotae 

 engorged larvae can metamorphose into nymphs in 13 days. Four 

 nymphs survived 121 days. 



Remarks : Although E. hiteodema and E. marmotae are easily 

 distinguished morphologically and their known geographic ranges 

 are widely separated, the two species are very similar. Collections 

 of both are scant, but there is apparently a host preference for 



