Elementary Study of Insects

<h2><SPAN name="Chapter_XI" id="Chapter_XI"></SPAN><span class="smcap">Chapter XI</span> <br/><br/>THE COLORADO POTATO BEETLE</h2> <div class="figright"> <ANTIMG src="images/037.png" width-obs="183" height-obs="300" alt="" title="" /> The Colorado potato beetle showing stages of development and work on a potato plant. Note the small patch of eggs and different sized grub on the plant and the grub, pupa and adult at side.</div> <p class="cap"><span class="dcap">This</span> is one of the worst pests of the potato. As the name would imply it came originally from Colorado but is common now all over the country. The full grown insect is short and thick with a hard shell, striped with yellow and black. The grubs, on the other hand, are soft and red or orange with black spots. Both the grubs and the beetles feed on potatoes and often completely strip them of their leaves. Since they feed on foliage they can be very quickly destroyed by dusting or spraying the plants with a poison such as Paris green or arsenate of lead. The patches of yellow or reddish eggs are found mostly on the under side of the potato leaves. When the fat grubs are<span class="pagenum"><SPAN name="Page_84" id="Page_84">[84]</SPAN></span> full-fed they go into the ground and change to pupae and later to the striped beetles. This pest should not be mistaken for the so-called old-fashioned potato beetles which are long and slender and either bluish grey in color or striped with yellow and black. These are blister beetles and are entirely different.</p> <h3><span class="smcap"><SPAN name="Observations_and_Studies3" id="Observations_and_Studies3"></SPAN>Observations and Studies</span></h3> <p>Watch for the first appearance of the adult beetles in the spring when the potatoes are just beginning to come up. They pass the winter under ground and in the spring come out ready to lay eggs on the young potatoes. Collect and examine the adults. How many stripes have they? Collect packets of eggs and count them. How many eggs in most packets? How are they attached to the leaf? How large are the grubs when they hatch from the egg? Examine the grubs where they are feeding on potatoes. Do they eat holes through the leaf, or do they eat away<span class="pagenum"><SPAN name="Page_85" id="Page_85">[85]</SPAN></span> the entire leaf? How fast do they grow? Collect a few in a glass tumbler. Feed them and watch them grow. What do they do when you touch them? What does the hard backed beetle do when it is touched? Collect some of the large grubs with tightly stuffed bodies and put them in a jar with dirt or sand and see where they<span class="pagenum"><SPAN name="Page_86" id="Page_86">[86]</SPAN></span> go. After a week dig them out and see what they look like.</p> <p>Write a short description of the eggs, grubs and beetle, its work and means of killing it when it is feeding on potatoes. Make careful drawings of a cluster of eggs, the grub and the beetle.</p> <hr style="width: 65%;" /><p><span class="pagenum"><SPAN name="Page_87" id="Page_87">[87]</SPAN></span></p> <div style="break-after:column;"></div><br />