July 1,1924 
Tarsostenus univittatus 
51 
seen, especially when the latter moves. 
It occupies nearly the entire egg. 
After a period of incubation of about 
10 days the larva becomes quite active 
and is ready to emerge. It twists and 
turns, causing the closely-fitting egg¬ 
shell to follow the movements of its 
body. At that time, just before hatch¬ 
ing, part of the segments assume a 
violet tint and the mandibles can now 
be seen. 
The process of hatching is a very 
interesting one and is accomplished in 
a manner which again is similar to 
what we find in Lyctus planicollis (fig. 
1 , e-l). 
When ready to emerge, the larva 
begins to push against the posterior 
end of the egg by alternately contract¬ 
ing and expanding its body (fig. 1, e). 
The ninth abdominal segment is armed 
with stiff setae which are used for 
piercing the eggshell. First one (fig. 
1 , /) and then several setae may be 
seen protruding through the end of 
the shell (fig. 1, g). Next, the ab¬ 
dominal segments may be seen gradu¬ 
ally working themselves out (fig. 1, 
h-k), until finally the larva frees itself 
completely and starts to crawl about 
(fig. 1,0. 
Under natural conditions the entire 
process of emerging probably takes less 
than an hour, but in the laboratory, 
when the eggs were placed in a plaster 
cell and little opportunity given for 
holding the shell in place, it took three 
hours. When, however, the cephalic 
end of the shell was held fast the pro¬ 
cess was completed in considerably less 
time. From this fact it occurred to the 
writer that the reason why eggs of this 
type have the peculiar strandlike pro¬ 
cess at the cephalic pole is that it 
enables the adult to attach the strand 
to the wood in order that the egg can 
be held in place while the larva emerges. 
In one instance a larva was unable to 
emerge from the egg after twisting and 
turning for a long time, presumably 
owing to the fact that the egg was not 
held in place. 
THE FIRST-STAGE LARVA 
The first-stage larva is armed with 
setae which are much longer than in the 
mature specimens. 5 When the larva is 
in the egg these setae are pressed close 
to the body, but as soon as the segments 
are free from the eggshell the setae 
straighten out. The newly hatched 
larva is nearly white except for the 
violet markings on the segments; the 
ampullae are slightly developed on the 
terga of the 6th and 7th abdominal 
* A. G. BSving ( 1 ) has described and figured the 
segments, a characteristic also of the 
mature larva. The mandibles, cerci, 
and claws are lightly chitinized, and 
four ocelli are present on each side of 
the head, also as in the mature larva. 
It has not been possible to find any 
spiracles. 
SUMMARY 
Tarsostenus univittatus (Rossi) be¬ 
longs to the family Cleridae, which is 
of considerable economic importance 
because of the predacious habits of the 
beetles in both the larval and adult 
stages. Several adults were reared 
from ash lumber infested with the 
powder-post beetle Lyctus planicollis 
Le Conte, on which it is known to be 
predacious. 
Under normal conditions the beetles 
pass the winter in the larval stage and 
adults emerge in the spring about the 
time the powder-post beetles appear. 
Oviposition begins soon after the 
adults mate; elongate, cylindrical, gray¬ 
ish-white eggs, which possess a peculiar 
strand-like process on the cephalic end, 
are deposited in or near the entrance 
gallery of their host. The process is 
probably attached to the wood to hold 
the eggshell in place while the larva 
emerges. After a period of incubation 
of about 10 days, the larva hatches 
from the egg by backing out, freeing 
itself by using its long, stiff caudal 
setae to pierce and break the posterior 
end of the shell. 
The first-stage larva differs from the 
mature form in that the setae are much 
longer, but resembles it in having 
violet-colored markings on its segments; 
ampullae present on the sixth and seventh 
terga; the mandibles, claws, and cerci 
lightly chitinized; and four ocelli on 
each side of the head. 
LITERATURE CITED 
(1) BSving, A. G., and Champlain, A. B. 
1920. LAKVAE OF NORTH AMERICAN BEETLES OF 
THE FAMILY CLERIDAE. PrOC. U. S. Nat. MUS. 
57: 575-649. 
(2) Burke, H. E., Hartman, R. D., and Snyder 
T. E. 
1922. the lead-cable borer or "short-circuit 
beetle” in California. U. S. Dept. Agr. 
Bui. 1107, 56 p., illus. 
(3) Hopkins, A. D., and Snyder, T. E. 
1917. POWDER-POST DAMAGE BY LYCTUS BEETLES 
to seasoned hardwood. Farmers’ Bui. 778, 
U. S. Dept. Agr., 20 p., illus. 
(4) Snyder, T. E. 
1916. EGG AND MANNER OF OVIPOSITION OF 
lyctus planicollis. Jour. Agr. Research 6: 
273-276, illus. 
(5) Snyder, T. E., and St. George, R. A. 
1924. determination of temperatures fatal 
TO THE POWDER-POST BEETLE LYCTUS PLANI¬ 
COLLIS LE CONTE BY STEAMING INFESTED ASH 
and oak lumber in a kiln. Jour. Agr. Re¬ 
search 28: 1133-1138, illus. 
ature larvae of this family. 
