[37 



2. THE IJOSY FOREST CATERPILLAR (Dryocampa mUmmda, Fab.) 



Order, LEriDOFTERA ; Family, Dryocampa. 



Tho last described insect, .as we have seen, attacked the wood only of the trees, but 

 the insects we are about to treat of devour the leaves, and by their attacks on the young 

 buds materially affect the growth of tho young maples. 



The name Dryocamjja, signifying oak or forest caterpillar, was originally applied by 

 the late Dr. Harris, the talented Entomologist of the State of Massachusetts, to certain 

 insects found sometimes in great numbers on oak trees, and of which one species, Dryocampa 

 tenatoria is exceedingly common in tlie larval state. The Ruby Forest Caterpillar, how- 

 ever, is generally found on the silver maple, acer dasycarpum, or the .swamp maple, acer 

 rubrum. 



The caterpillars are hatched about the month of July, and their presence may often 

 be detected by their droppings on the ground beneath the trees, although it is not always 

 easy to di.scover the insect itself. Mi-. William Saunders has })red the moth from the 

 larva, and we therefore avail ourselves of his description puljlished in the Canadian 

 Entomolofjist, Vol. 11., page 75. 



The larva when full grown is about one inch and three quarters long. The head- is 

 rather email, flattened and bilobed in front, of a pale orange colour, and having a black 

 dot on each side below, near the mandibles or jaws. The body above is yellowish white, 

 with a stripe of rather indistinct pale green on the back, and three stripes of the same 

 hue on each side. The third mjment has two hlark horns fully one tenth'of an ineh'loiiij, one 

 on each side of the dorsal stripe, and spreading outwards. On each segment are several 

 black dots or tubercles, those on the twelfth and thirteenth segments being the most 

 di.stinct. On the sides of the posterior segments is a pale reddish, orange patch, nearly 

 the colour of the head. The under surface is deep, glossy green, with a faint whitish 

 line down the middle, and many small blackish dots or tubercles. The feet are pale 

 leddish ; the pro-legs pale green, dotted with black. 



The larv;« having arrived at maturity seek shelter iu the ground, and there undergo 

 their transformation into the pupal state, remaining thus all the winter and spring, and 

 emerging as perfect moths the following summer. The method by which the apparently 

 inanimate pupa effects its escape has been well described by Dr. Harris in writing of a 

 very similar insect — the Dryocampa imperialis: " The Chrysalis is rough with little ele- 

 vated points, particularly on the anterior extremity, and ends Ijehind with a long forked 

 spine, and is surrounded on each ring with a notched ridge, the little teeth of which point 

 towards the tail. Three of the grooves or incision.s between the rings are very deep, thus 

 allowing a greiit extent of motion to the joints, and these with the notched ridges and the 

 long spine at the end of the body, enable the chrysalis to work its way upwards in the 

 eartii above tiie surface of which it pushes the fore pai-t of its body just before the moth 

 makes its escape." 



j-ijj. 27. Tlie perfect insect, of which Fig. 27 represents the 



Tnale, is a very beautiful and delicately coloured creature. 

 The fore\vings are rose coloured crossed by a broad pale 

 yellow band ; the hind wings are pale yellow with a 

 short rosy ban<l behind the middle, this in some speci- 

 mens es])ecially males is wanting ; the body is yellow ; 

 the abdomen and legs are rose coloured. The male 

 expands about one inch and three ([uarters, while the 

 Colours- Pale yellow and rose. female reaches fully two inches, the body of the male 

 does not extend beyond the hind wings as does that of the female. The antennas of the 

 latter are simple and thread like in form while those of the male, as will be seen on refer- 

 ring to the figure, areileeply pectinated or comb .shaped to nnuh beyond half their length, 

 and minutely serratW or saw-shaped from thence to the tips. Dr. Harris, conjectured 

 that sometimes two broods might occur in the season ; as in 1841;, he capture.l sjjecimens 

 of the larvaj in July which produced the moth in August, and in September following, he 

 took m.any more caterpillars. He, however, accounted for this on the ground, " that all 

 insects liave theii- periods of increased numbers which in some instances may be unfixed 



