Il6 ENTOMOLOGICAL NEWS. [June, 



pale; hair bristly, blackish, appearing foxy red next the body. The larva 

 resembles the dark brown form of Spilosoma virginica in appearance. 



Cocoon formed of the larval hairs held in place with silk as in other 

 , species of Spilosoma. 



Pupa robust; nearly straight along the ventral line, slightly contracted 

 along the ventral line, slightly contracted laterally behind the thorax. 

 Abdomen large, rounded, the last segments tapering rapidly; cremaster 

 flat, short and thick, furnished with many short knobbed spines. Thorax 

 and cases creased; body coarsely, but densely punctured. Color pitchy 

 black, shiny, the spiracles pale reddish. 



The larva matured and began to form its cocoon September 3d, 

 giving a larval period of over ten weeks. A male imago emerged 

 in a warm room on March i2th, the next year. 



It will be observed from the measurements given above that 

 the widths of head follow the calculated series well, except the 

 ninth stage, which is entirely superfluous, being inserted as a 

 geometric mean between the eighth and tenth stages at a much 

 higher ratio than any other stage, viz., calculated, .4, .5, .7, .9, 

 i.i, 1.3, 1.7, 2. i, 2.6, 3. 2, ratio .80, giving but ten stages; found 

 .3, .4, .6, .9, i.i, 1.3, 1.6, 2.1, 2.3, 2.6, 3.1. The ratio between 

 the 8th, 9th and loth stages as found is .90, which, if kept up, 

 would interpolate an extra stage between every one. Does this 

 indicate that this species has normally but ten stages, and that the 

 9th as observed by me is unusual, being produced by scarcity of 

 food or some other cause ? It is to be noted that I did not find 

 its markings to differ at all from those of the roth stage. 



Mr. Hulst, in the brief, but only published account of this spe- 

 cies,* apparently found but six larval stages, but in the absence 

 of any measurements it is useless to speculate on this. While I 

 do not deny that the number of stages of this as well as other 

 species, may be subject to variation under varying conditions of 

 climate or food, or even under normal conditions, I hold that it 

 is very far from having been proved. This will require accurate 

 observation, in my opinion best accompanied by measurements, 

 so that it can be seen where the variation, if any, occurred, as 

 well as to serve as a check on the accuracy of the work.f 



Food-plants. The larvae are probably omnivorous. Though 

 found on ash, they seemed to prefer various herbaceous plants 

 as they became older. Larvae from Dutchess County, New York. 



* Bull. Brooklyn Ent. Soc. viii, 120. f-See further Psyche, v, 420. 



