TROMBIDIIDAE OF MINNESOTA 113 
the base of the cephalothorax on the dorsum and posterior to the 
genital opening on the ventral side is usually brighter colored. Size: 
3.75 to 5 mm long by 2 to 2.5 mm wide. The males are smaller. Body 
constricted near the middle, widest anteriorly, covered thickly with 
slender plumose hairs. On the dorsum of abdomen three transverse 
grooves and a median posterior depression; on the venter two trans- 
verse grooves; genital opening posterior to coxae IV, anal opening 
nearer to the posterior margin than to the genital opening. Cephalo- 
thorax wider than long, the base somewhat concealed by the overhang- 
ing abdomen. Dorsal groove expanded a little posterior of the middle. 
Eyes on long pedicels located a little further anterior than the expan- 
sion of the dorsal groove. Palpi with segment II nearly three times 
as long as segment I and considerably swollen, segment III about a third 
of segment II in length, 1V twice as long as III, with a single stout claw 
at its tip. The thumb is as long as or longer than segment IV, a little 
clavate in outline. Mandibles long and slender. 
The legs are long and slender. Between the claws at the tip of 
the tarsi is a hairy pulvillus. Tarsus of leg I not swollen. The male 
differs from the female in its smaller size, more pronounced dorsal and 
ventral grooves, and shorter and wider genital opening. 
Nymph. Similar to the adults except in the following points: 
body smaller in proportion to the length of the legs, covering of hairs 
more sparse, cephalothorax and legs yellowish, while the body is dark 
orange colored, cephalothorax larger in proportion to the size of the 
body, and tarsi I slightly swollen. Size unengorged, 0.45 x 0.35 mm, 
engorged 0.80 x 0.60 mm. 
Larva. Unengorged: color scarlet, size 0.30 mm long by 0.20 mm 
wide. Elliptical in outline, widest near the middle, ends broadly 
rounded. On the dorsal side an anterior chitinous plate or shield 
nearly a third of the length of the body and irregularly pentagonal 
in outline. Near the lower central portion a pair of very large pits 
from each of which arises a long slender barbed hair, three other 
pairs of stout barbed hairs near the margins. The paired eyes just 
laterad of posterior angles of this shield. A smaller elliptical plate 
just posterior to and contiguous to the anterior plate. Numerous 
heavy barbed spines on the abdomen. Ventral side with spines similar 
to the dorsum. Coxae very large, I and II contiguous, III separated 
slightly from II. Opening to tracheal system between I and II. The 
mouth parts are hidden beneath the dorsal shield. Palpi short and swol- 
len, segment IV with a heavy bifurcate terminal claw and a smaller 
simple post-terminal claw. Thumb papilla-like with two very long 
