MICHIGAN ACADEMY OF SCIENCE. 
101 
A CASE OF POSSIBLE PARASITISM 
IN THE LEPIDOPTERA. 
R. H. Pettit. 
On Aug. 19, 1905, several tomato-worms, Pklegutontius sexto, were placed 
in a cage for the purpose of rearing the adults. On the following day, these 
larvae buried themselves in the soil of the cage,' which was placed in the 
window insect ary to remain until the following summer. 
On Sept. 10, 1906, there were seen, flying about in the cage, a number of 
small tiniid moths, their pupa skins projecting from the surface of the soil 
where were concealed the dirt covered cocoons from which they came. These 
cocoons were fastened together loosely with silk, which also was spun out 
into the soil for some little distance. The pupal cases of the tobacco- worms-, 
were found on examination, to be empty and dried up. Several cocoons 
were found attached to the pupal skins. 
This rearing of a tiniid moth from the pupa of a much larger moth was 
sufficiently astonishing, though of course we could not feel sure that the 
larvae or eggs af the tiniids were not in the foil to begin with, and that they 
had not developed at the expense of animal matter already there. It was, 
therefore, decided to repeat the experiment under more exact conditions, 
and to this end a cage was prepared by Mr. E. J. Kraus, Assistant in charge 
of breeding experiments. A good sized flower-pot was filled with soil in 
the usual way, and a glass cylinder was set over it and covered with swiss 
muslin in the usual way, so as to exclude everything from the outside. A 
pot containing the soil was then taken out and steamed for several hours, 
thoroughly cooked with dry steam, the cylinder was then replaced and when 
everything had cooled off sufficiently, a fresh lot of tobacco-worm pupae 
were introduced. This was done on Apr. 25, 1907, the pupae having been 
obtained during the plowing of an old tobacco field. Seven pupae were 
secured and placed in the sterile cages, and on Aug. 1907. two more tiniid 
moths appeared. On the 18th of July, one adult tobacco nioth was obtained. 
A determination by Mr. Busck, of the Bureau of Entomology, p aces the 
creature as a well-known species, Tinia pellionella or the common clothes- 
moth. Now the clothes-moth feeds on dried animal matter, loving woolen 
goods best of all, and it is of course possible that it may have been feeding on 
dead pupae. We debated the question of dissecting some of the tobacco 
worm pupae, and of looking for foreign organisms, but decided not to because 
of lack of material and because the larvae of the Tinis would have been very 
small at that time. 
In any case, this is a new and hitherto unknown habit in an old and well- 
known species. It shows how easily and naturally parasitic habits might 
be developed, the tiniid gradually working over from dead to diseased and 
finally to living hosts. There is one intance of true parasitism known in 
the order Lepidoptera, that of Euclemsia bassettello which works inside 
one of the oak coccids of the genus Ivermes. The life-history of this species 
was discussed at a previous meeting of this society. 
We hope to secure enough larvae and pupae this fall to be able to spare a 
number for dissection, even if we have to grow a few plants for the purpose. 
Michigan Agricultural College. 
Received for publication, April 4, 1908. 
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