CH. XVIII.] PARASITICAL INSECTS, ETC. 257 



ily detected upon the sheet of paper. These larvae 

 changed into small coleopterous insects. 



There are also galls formed by caterpillars, in 

 which they undergo their metamorphoses into a but- 

 terfly. Reaumur relates that he received some galls 

 from the Island of Cyprus. They grew upon a spe- 

 cies of limonum, and each is borne like fruit by a 

 short stalk. They are of about the figure and size 

 of a nut, and seem to have a kind of small head or 

 crown at the part opposite to the stalk. When first 

 received they were of a pale gray, their surface tol- 

 erably smooth, but a little cottony. They must be 

 classed with the woody and indurated galls ; their 

 first layers, those nearest the exterior envelope, are, 

 notwithstanding, spongy, but the interior layer, that 

 which forms the coat of the cavity, is very hard. 

 This cavity is much larger than that of the majority 

 of the galls ; it is a very large dwelling, and is in- 

 habited by a true caterpillar. He opened many of 

 these galls, in each of which he found the caterpillar 

 dead and dry, and consequently in a state that did 

 not admit of description ; all that he could discern 

 was that it was smooth, but he could not detect the 

 number of its prolegs, which were too much with- 

 drawn within the body. Although the caterpillar 

 was no longer alive, yet some of its modes of life 

 could be easily distinguished ; it apparently gnawed 

 the interior of the gall in the manner of the larvae of 

 the willow-gall. When its time of change arrives it 

 pierces the gall, which it does by a foresight similar 

 to what we have admired in some caterpillars of 

 wheat. This caterpillar consequently changes the 

 gall itself while in this state, and, having teeth, it 

 pierces a hole, which it could not do when a butter- 

 fly, — the aperture by which it makes its escape. 

 When the hole is made, the caterpillar no longer 

 takes food ; it spins a cocoon of white and brilliant 

 silk, the tissue of which is very thin, but compact. 

 This cocoon lines the interior of the cavity, and even 

 Y 2 



