280 STATE BOARD OF AGRICULTUEE. 



WHEEE ARE THE EGGS LAID? 



I do not know as anybody has ever seen the eggs laid, or found them in posi- 

 tion after they were laid. Yet in this case analogy is nearly as satisfactory as 

 actual observation ; and analogy i)oints to the stems of plants of the grass fam- 

 ily and the sedge family as the j^lace of deposit. We find that instinct, that 

 mysterious faculty which puzzles even the wisest philosophers, impels all insects 

 to place their eggs on or near the food which their young or larvre are to feed, 

 even though this food has no joart in the diet of the mother insect. The wasp 

 sips the honeyed sweet of flowers, yet she never forgets to place her egg in the 

 cajitured grub or caterpillar which she has imprisoned in her earthen cell. Our 

 common house-fly has a taste which the veriest epicure would respect : yet her 

 eggs are placed in the filthy ordure of the horse-stable ; and as you all know, 

 the potato-beetle lays its eggs on its food plant, the codling moth on the apple, 

 the curculio on the plum and peach, the various borers on the trees which are 

 fitted to nourish their young, and so on of the whole order. Mistakes, which 

 would certainly prove fatal, we have every reason to suppose are of very rare 

 occurrence. Hence, as we know that the larva? of the Leuconia unijnmcta 

 — the so-called army worms — feed on the plants of the two families Graminefe 

 and Cyperacea?, or the grass and sedge families, we are safe in asserting that 

 the eggs are laid either on the grasses, which include our common grains, as 

 wheat, barley, oats, and corn, or the sedges, which are generally known as 

 wild grasses. Both Professor Eiley and Dr. Fitch think the eggs are usually 

 laid on plants which grow on low ground. I have some doubt if such discrim- 

 ination is practiced. The eggs remain as such not only through the autumn, 

 but also through the next winter, even to the next June. I am speaking for 

 Michigan. 



LAEVJ5. 



The young caterpillars (see Fig. 2) come forth from the tiny eggs during 



the last days of June. These are black 

 striped with yellow, and bear a close resem- 

 blance to some of our common cut-worms. 

 Their appearance changes but little with 

 growth, except in their ever increasing size. 

 When fully matured they are about one and 

 one-half inches in length. I need hardly 

 say that these caterioillars have the usual 

 ^^^- ^- number of legs, six true, and ten false ones. 



These larva? develop in about four weeks, but are not seen excejit in sucli sea- 

 sons as the last, when their excessive numbers attract general attention. Even 

 when they are so iramerous they are seldom noticed till after they are at least 

 half -grown. At this stage or later, their food plants are swept away as by fire, 

 and thus these larvae migrate in armies whose numbers defy computation. 

 Eoads are covered with a living carpet, which if not three-ply is three deep. 

 Eailroad trains are stopped and whole fields of grain vanish in a night. I 

 remember in 1861 to have seen such an army cross a lane. It was impossible 

 to pass along, without crushing myriads of these caterpillars. Fences were 

 entirely covered, and though this was at five oclock in the afternoon, still an 

 eight acre field of oats, which they were just charging upon, was entirely ruined 



