Latin: Caradrina clavipalpis
The Pale Mottled Willow is part of the night butterfly family. They morph from larvae to the pale mottled willow. In the larvae stage are known to live under and in roofs, which is how it got its danish name “roof worm”.
Appearance
The “roof worm” is a larva of a butterfly. The larva will transform or morph into a butterfly. When it is a larva, it will be gray, brown, white and look like other butterfly larvae. Butterfly larvae have a main capsule, legs and what are called wart feet.
Biology and behavior
As mentioned, this larva is often found on or under different roofs, which gave it the name “roof worm”. It will typically be thatched roofs of straw. The reason why it is found here is that the “roof worm” lives on grass and hay and is therefore brought to the house with these materials for the roof. The “roof worm” therefore often appears when you are in the process of laying a new thatched roof. Because of their way of life, they are also often found on attic on which you keep hay.
The larva lives in and around the thatched roof or on the attic during the warmer months, after which they appear in the house during the colder months. Here they are trying to find a warmer place where they can spend the winter inside its own web. It is during that time you often would notice the “roof worm”, when it tries to find a new hiding place. When winter is over and the warmer spring weather starts, the larva emerges from its homemade pupa and transforms into a butterfly.
Damage
The “roof worm” is not harmful in any way, as it cannot sting or bite. However, it can be annoying when you are in the process of laying a new thatched roof, and they just suddenly peep out. The “roof worm” can however gnaw in different places in the roof as well as on textiles. The damage is however it not that great, but it can be annoying. They gnaw in the roof before they start the to create their pupa in the winter.
Prevention and pest control
The “roof worm” can be irritating on and around thatched roofs, but often they will not accrue in larger numbers. It is possible to remove them one by one without much trouble. You can use an insect powder, which you put in the places where the “roof worm” appears. This will often be in the attic or closer to the roof. If you do have cloths lying in the attic, it is advisable to remove them as long you have Pale Mottled Willow larvae in the attic, as both the insect powder as well as the larvae may ruin your cloth.
When the worm morph into a butterfly, they will not return to the same roof to lay eggs again. Therefore, you can be sure that they are gone if you have removed them in the first place. You do not necessarily need to control them as they will disappear by themselves eventually.
"Pests in House and Home"
"Bed Bugs - Bites, Stings and Itches"
"Food Pests"
"Husets dyreliv" (Insects Around the House - Only danish)
"Skadedyr i træ" (Timber Pests - Only danish)
"Stuefluen" (Common Housefly - Only danish)