TROMBIDIIDAE OF MINNESOTA 127 
Trombidium parasiticum Murray—Econ. Ent. p. 129; 1877. 
Trombidium muscarum Riley. Ist Rpt. U. S. Ent. Comm. p. 306; 
i878s\\ Banks rans. 7Am> Mate Soc. Volk Zit spre2 13; 
1894. 
Microtrombidium muscarum Ewing. Ill. Univ. Studies, Vol. 3, 
Paco, EGOS: 
The adult of this species has not been collected in Minnesota but 
must occur here, as what is probably the larva has been found three 
separate times, twice on adult W. domestica, (April 8, 1916, and July 
8, 1914), and once in a manure pile (August 11, 1914). They were 
true trombidium larvae. The description follows: 
Larva, partly engorged. Color scarlet, size 0.50 to 0.66 mm long 
by 0.35 to 0.45 mm wide. Oval in outline, widest a little before the 
middle, Dorsum with numerous branched hairs. On the anterior end 
a large pentagonal chitinous shield widely rounded on the anterior 
angle, three heavy spines near each of the lateral edges, two of these 
branched, the middle one unbranched and borne in a large pit; a pair 
of hairs near the anterior angle. Just laterad of this anterior shield, 
on either side, are the paired eyes on small elliptical plates. Just pos- 
terior is a narrow more or less spindle-shaped plate bearing a pair of 
branched hairs. Ventral surface with fewer hairs. Coxae I and II 
contiguous, with opening to tracheal system between. Coxae III sep- 
arated from the others. Mouth parts completely hidden beneath the 
dorsal plate. Mandibles concealed inside of a cylindrical sheath which 
bears on its under surface two palmate appendages. Palpi short and 
stout, segments subequal, segment IV ends in a bifurcate sword-shaped 
claw, bearing a spine at its base. Thumb papilla-like, surmounted on 
the tip by several very long finely branched hairs. Legs slender, claws 
of tarsi normal, those of tarsus III like tarsi I and II. 
Sericothrombium scabrum (Say) 
Trombidium scabrum Say—J\. Acad: Nat. Sci. Phila., Vol. 2, pt. I, 
prolselsZ i: 
Le Conte, Comp. Writings of Say. Vol. 2, p. 16; 1859. 
Banksy Drans. Am. Ent: Soc, Vol.-21*p. 212; 1894 
bynes. Vl Unive Studies, Vol. 3, No:-0,p.90); 1909. 
Adult female. Color, bright scarlet, pale on under side. Size, 
2.25 mm to 5 mm long by 1.50 to4 mm wide. Body strongly constricted 
in the middle, very wide in front, narrow behind, posterior edge 
rounded with a prominent indentation at the median point. The 
grooves on the dorsal surface form an angular figure 8. The ventral 
surface has anterior transverse groove, followed by a second and a 
