The caterpillars of this insect congregate in colonies and surround themselves with a web which often reaches the size of a foot or more in diameter. These webs are common on trees in July and August. Cutting off the webs or burning them on the twigs is the most practical remedy.
Fig. 105.—Branch Showing Work of the Leopard Moth Larva.
The Leopard Moth
Life history: This insect does its serious damage in the grub form. The grubs which are whitish in color with brown heads, and which vary in size from 3/8 of an inch to 3 inches in length ([Fig. 104]), may be found boring in the wood of the branches and trunk of the tree all winter. [Fig. 105]. The leopard moth requires two years to complete its round of life. The mature moths are marked with dark spots resembling a leopard’s skin, hence the name. [Fig. 106]. It is one of the commonest and most destructive insects in the East and is responsible for the recent death of thousands of the famous elm trees in New Haven and Boston. [Fig. 107].
Fig. 106.—The Leopard Moth.
Remedies: Trees likely to be infested with this insect should be examined three or four times a year for wilted twigs, dead branches, and strings of expelled frass; all of which may indicate the presence of this borer. Badly infested branches should be cut off and burned. Trees so badly infested that treatment becomes too complicated should be cut down and destroyed. Where the insects are few and can be readily reached, an injection of carbon bisulphide into the burrow, the orifice of which is then immediately closed with soap or putty, will often destroy the insects within.