110 BULLETIN 190, UNITED STATES NATIONAL MUSEUM 



PODOSESIA SYRINGAE race FRAXINI (Lugger) 



Trochiliiim fraxini Lugger, Psyche, vol. 6, p. 109, pi. 3, fig. 4, 1891 ; 1st Ann. Rep. 



Ent. State Exp. Stat. Univ. Minnesota, 1895, p. 94 (1895). — Aldrich, Insect 



Life, vol. 4, p. 68, 1891. 

 Aegeria fraxini Orcutt and Aldrich, South Dakota Agr. Coll. and Exp. Stat. Bull. 



22, pp. 80-83, fig. 1, 1891. 

 Podosesia fraxini Beutenmuller, Bull. Amer. Mus. Nat. Hist., vol. 6, p. 88, 1894; 



vol. 8, p. 125, 1896; vol. 9, p. 219, 1897; Mem. Amer. Mus. Nat. Hist., vol. 1, pt. 



6, p. 245, pi. 30, fig. 15 (female), 1901.— McDunnough, Check list of the 



Lepidoptera of Canada and the United States of America, pt. 2, No. 8769, 1939. 



Male. — Antennae pale rufous, with narrow black ambulations above. 

 Labial palpus with a heavy brush, rufous slightly mixed with black. Head 

 grizzly black on top, base fringed with orange. Collar brown and yellow. 

 Thorax brown-black, tufted with yellow at wing base and black and yellow 

 on metathorax laterally. Abdomen contracted at base, segment 1 black ; 

 segments 2 and 3 black, narrowly edged with yellow; segment 4 black, 

 broadly banded with yellow; segments 5, 6, and 7 and the short, pointed 

 anal tuft chestnut mixed with yellow. Coxae black, posterior tibiae deep 

 yellow or orange, black between the spurs. Tarsi with first joint very long, 

 sordid yellow. Forewing opaque, coppery brown to discal mark, hyaline 

 streaks between the veins to wing base ; costa and inner margin dull black, 

 red on basal parts; fringes dark brown. Hindwing transparent; veins 

 yellowish brown ; narrow margin edged with red ; fringes sordid brown, 

 darkening toward base. 



Female. — Very similar to male. Abdomen less constricted at base. 

 Hindwing more broadly margined and with reddish suffusions between 

 veins lb and Ic. 



Expanse : Male 28-32 mm., female 30-34 mm. 



Distribution. — Northern Midwestern States to Manitoba, and Kansas, 

 Colorado, Rocky Mountain regions to Montana. Not recorded from the 

 Pacific coast. 



Type. — Location not indicated. 



Remarks. — In its western distribution the ash tree borer, Podosesia 

 syringae, is replaced by the pale ochreous color form fraxini. Heretofore 

 fraxini has been given specific rank, but it is conspecific with syringae as 

 shown in a series of examples from St. Paul, Minn., a, transition zone in 

 which the two color forms occur intermixed. In arid regions west of the 

 Mississippi fraxini runs true to type. 



As examples of mimicry the Aegeriidae furnish many excellent illustra- 

 tions. It is of interest to note the similar response to climatic differences 

 in the insects which are mimicked. In the humid Atlantic coast regions, 

 Podosesia syringae resembles deceptively a common, black and chestnut 

 colored wasp of the genus Polistes; in the arid West, the race fraxini 

 mingles with a different Polistes of the sarne pale ochreous coloration. 



Among insects injurious to forest and shade trees, the ash tree borer 

 has called for considerable attention. Young trees planted along streets, 



